text(n)                      Tk Built-In Commands                      text(n)



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NAME
       text, tk_textCopy, tk_textCut, tk_textPaste - Create and manipulate
       text widgets

SYNOPSIS
       text pathName ?options?
       tk_textCopy pathName
       tk_textCut pathName
       tk_textPaste pathName

STANDARD OPTIONS
       -background           -highlightthickness  -relief
       -borderwidth          -insertbackground    -selectbackground
       -cursor               -insertborderwidth   -selectborderwidth
       -exportselection      -insertofftime       -selectforeground
       -font                 -insertontime        -setgrid
       -foreground           -insertwidth         -takefocus
       -highlightbackground  -padx                -xscrollcommand
       -highlightcolor       -pady                -yscrollcommand

       See the options manual entry for details on the standard options.

WIDGET-SPECIFIC OPTIONS
       Command-Line Name:-autoseparators
       Database Name:  autoSeparators
       Database Class: AutoSeparators

              Specifies a boolean that says whether separators are
              automatically inserted in the undo stack. Only meaningful when
              the -undo option is true.

       Command-Line Name:-blockcursor
       Database Name:  blockCursor
       Database Class: BlockCursor

              Specifies a boolean that says whether the blinking insertion
              cursor should be drawn as a character-sized rectangular block.
              If false (the default) a thin vertical line is used for the
              insertion cursor.

       Command-Line Name:-endline
       Database Name:  endLine
       Database Class: EndLine

              Specifies an integer line index representing the line of the
              underlying textual data store that should be just after the last
              line contained in the widget. This allows a text widget to
              reflect only a portion of a larger piece of text. Instead of an
              integer, the empty string can be provided to this configuration
              option, which will configure the widget to end at the very last
              line in the textual data store.

       Command-Line Name:-height
       Database Name:  height
       Database Class: Height

              Specifies the desired height for the window, in units of
              characters in the font given by the -font option. Must be at
              least one.

       Command-Line Name:-inactiveselectbackground
       Database Name:  inactiveSelectBackground
       Database Class: Foreground

              Specifies the colour to use for the selection (the sel tag) when
              the window does not have the input focus. If empty, {}, then no
              selection is shown when the window does not have the focus.

       Command-Line Name:-insertunfocussed
       Database Name:  insertUnfocussed
       Database Class: InsertUnfocussed

              Specifies how to display the insertion cursor when the widget    |
              does not have the focus. Must be none (the default) which means  |
              to not display the cursor, hollow which means to display a       |
              hollow box, or solid which means to display a solid box. Note    |
              that hollow and solid will appear very similar when the          |
              -blockcursor option is false.

       Command-Line Name:-maxundo
       Database Name:  maxUndo
       Database Class: MaxUndo

              Specifies the maximum number of compound undo actions on the
              undo stack. A zero or a negative value imply an unlimited undo
              stack.

       Command-Line Name:-spacing1
       Database Name:  spacing1
       Database Class: Spacing1

              Requests additional space above each text line in the widget,
              using any of the standard forms for screen distances. If a line
              wraps, this option only applies to the first line on the
              display. This option may be overridden with -spacing1 options in
              tags.

       Command-Line Name:-spacing2
       Database Name:  spacing2
       Database Class: Spacing2

              For lines that wrap (so that they cover more than one line on
              the display) this option specifies additional space to provide
              between the display lines that represent a single line of text.
              The value may have any of the standard forms for screen
              distances. This option may be overridden with -spacing2 options
              in tags.

       Command-Line Name:-spacing3
       Database Name:  spacing3
       Database Class: Spacing3

              Requests additional space below each text line in the widget,
              using any of the standard forms for screen distances. If a line
              wraps, this option only applies to the last line on the display.
              This option may be overridden with -spacing3 options in tags.

       Command-Line Name:-startline
       Database Name:  startLine
       Database Class: StartLine

              Specifies an integer line index representing the first line of
              the underlying textual data store that should be contained in
              the widget. This allows a text widget to reflect only a portion
              of a larger piece of text. Instead of an integer, the empty
              string can be provided to this configuration option, which will
              configure the widget to start at the very first line in the
              textual data store.

       Command-Line Name:-state
       Database Name:  state
       Database Class: State

              Specifies one of two states for the text: normal or disabled. If
              the text is disabled then characters may not be inserted or
              deleted and no insertion cursor will be displayed, even if the
              input focus is in the widget.

       Command-Line Name:-tabs
       Database Name:  tabs
       Database Class: Tabs

              Specifies a set of tab stops for the window. The option's value
              consists of a list of screen distances giving the positions of
              the tab stops, each of which is a distance relative to the left
              edge of the widget (excluding borders, padding, etc). Each
              position may optionally be followed in the next list element by
              one of the keywords left, right, center, or numeric, which
              specifies how to justify text relative to the tab stop.  Left is
              the default; it causes the text following the tab character to
              be positioned with its left edge at the tab position. Right
              means that the right edge of the text following the tab
              character is positioned at the tab position, and center means
              that the text is centered at the tab position. Numeric means
              that the decimal point in the text is positioned at the tab
              position; if there is no decimal point then the least
              significant digit of the number is positioned just to the left
              of the tab position; if there is no number in the text then the
              text is right-justified at the tab position. For example, "-tabs
              {2c left 4c 6c center}" creates three tab stops at two-
              centimeter intervals; the first two use left justification and
              the third uses center justification.

              If the list of tab stops does not have enough elements to cover
              all of the tabs in a text line, then Tk extrapolates new tab
              stops using the spacing and alignment from the last tab stop in
              the list. Tab distances must be strictly positive, and must
              always increase from one tab stop to the next (if not, an error
              is thrown). The value of the -tabs option may be overridden by
              -tabs options in tags.

              If no -tabs option is specified, or if it is specified as an
              empty list, then Tk uses default tabs spaced every eight
              (average size) characters.  To achieve a different standard
              spacing, for example every 4 characters, simply configure the
              widget with "-tabs "[expr {4 * [font measure $font 0]}] left"
              -tabstyle wordprocessor".

       Command-Line Name:-tabstyle
       Database Name:  tabStyle
       Database Class: TabStyle

              Specifies how to interpret the relationship between tab stops on
              a line and tabs in the text of that line. The value must be
              tabular (the default) or wordprocessor. Note that tabs are
              interpreted as they are encountered in the text. If the tab
              style is tabular then the n'th tab character in the line's text
              will be associated with the n'th tab stop defined for that line.
              If the tab character's x coordinate falls to the right of the
              n'th tab stop, then a gap of a single space will be inserted as
              a fallback. If the tab style is wordprocessor then any tab
              character being laid out will use (and be defined by) the first
              tab stop to the right of the preceding characters already laid
              out on that line. The value of the -tabstyle option may be
              overridden by -tabstyle options in tags.

       Command-Line Name:-undo
       Database Name:  undo
       Database Class: Undo

              Specifies a boolean that says whether the undo mechanism is
              active or not.

       Command-Line Name:-width
       Database Name:  width
       Database Class: Width

              Specifies the desired width for the window in units of
              characters in the font given by the -font option. If the font
              does not have a uniform width then the width of the character
              "0" is used in translating from character units to screen units.

       Command-Line Name:-wrap
       Database Name:  wrap
       Database Class: Wrap

              Specifies how to handle lines in the text that are too long to
              be displayed in a single line of the text's window. The value
              must be none or char or word. A wrap mode of none means that
              each line of text appears as exactly one line on the screen;
              extra characters that do not fit on the screen are not
              displayed. In the other modes each line of text will be broken
              up into several screen lines if necessary to keep all the
              characters visible.  In char mode a screen line break may occur
              after any character; in word mode a line break will only be made
              at word boundaries.
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DESCRIPTION
       The text command creates a new window (given by the pathName argument)
       and makes it into a text widget. Additional options, described above,
       may be specified on the command line or in the option database to
       configure aspects of the text such as its default background color and
       relief.  The text command returns the path name of the new window.

       A text widget displays one or more lines of text and allows that text
       to be edited. Text widgets support four different kinds of annotations
       on the text, called tags, marks, embedded windows or embedded images.
       Tags allow different portions of the text to be displayed with
       different fonts and colors. In addition, Tcl commands can be associated
       with tags so that scripts are invoked when particular actions such as
       keystrokes and mouse button presses occur in particular ranges of the
       text. See TAGS below for more details.

       The second form of annotation consists of floating markers in the text
       called "marks".  Marks are used to keep track of various interesting
       positions in the text as it is edited. See MARKS below for more
       details.

       The third form of annotation allows arbitrary windows to be embedded in
       a text widget. See EMBEDDED WINDOWS below for more details.

       The fourth form of annotation allows Tk images to be embedded in a text
       widget. See EMBEDDED IMAGES below for more details.

       The text widget also has a built-in undo/redo mechanism. See THE UNDO
       MECHANISM below for more details.

       The text widget allows for the creation of peer widgets. These are
       other text widgets which share the same underlying data (text, marks,
       tags, images, etc).  See PEER WIDGETS below for more details.

INDICES
       Many of the widget commands for texts take one or more indices as
       arguments.  An index is a string used to indicate a particular place
       within a text, such as a place to insert characters or one endpoint of
       a range of characters to delete. Indices have the syntax
              base modifier modifier modifier ...
       Where base gives a starting point and the modifiers adjust the index
       from the starting point (e.g. move forward or backward one character).
       Every index must contain a base, but the modifiers are optional.  Most
       modifiers (as documented below) allow an optional submodifier. Valid
       submodifiers are any and display. If the submodifier is abbreviated,
       then it must be followed by whitespace, but otherwise there need be no
       space between the submodifier and the following modifier.  Typically
       the display submodifier adjusts the meaning of the following modifier
       to make it refer to visual or non-elided units rather than logical
       units, but this is explained for each relevant case below. Lastly,
       where count is used as part of a modifier, it can be positive or
       negative, so "base - -3 lines" is perfectly valid (and equivalent to
       "base +3lines").

       The base for an index must have one of the following forms:

       line.char   Indicates char'th character on line line. Lines are
                   numbered from 1 for consistency with other UNIX programs
                   that use this numbering scheme.  Within a line, characters
                   are numbered from 0. If char is end then it refers to the
                   newline character that ends the line.

       @x,y        Indicates the character that covers the pixel whose x and y
                   coordinates within the text's window are x and y.

       end         Indicates the end of the text (the character just after the
                   last newline).

       mark        Indicates the character just after the mark whose name is
                   mark.

       tag.first   Indicates the first character in the text that has been
                   tagged with tag.  This form generates an error if no
                   characters are currently tagged with tag.

       tag.last    Indicates the character just after the last one in the text
                   that has been tagged with tag. This form generates an error
                   if no characters are currently tagged with tag.

       pathName    Indicates the position of the embedded window whose name is
                   pathName.  This form generates an error if there is no
                   embedded window by the given name.

       imageName   Indicates the position of the embedded image whose name is
                   imageName.  This form generates an error if there is no
                   embedded image by the given name.

       If the base could match more than one of the above forms, such as a
       mark and imageName both having the same value, then the form earlier in
       the above list takes precedence. If modifiers follow the base index,
       each one of them must have one of the forms listed below. Keywords such
       as chars and wordend may be abbreviated as long as the abbreviation is
       unambiguous.

       + count ?submodifier? chars
              Adjust the index forward by count characters, moving to later
              lines in the text if necessary. If there are fewer than count
              characters in the text after the current index, then set the
              index to the last index in the text. Spaces on either side of
              count are optional. If the display submodifier is given, elided
              characters are skipped over without being counted. If any is
              given, then all characters are counted. For historical reasons,
              if neither modifier is given then the count actually takes place
              in units of index positions (see INDICES for details). This
              behaviour may be changed in a future major release, so if you
              need an index count, you are encouraged to use indices instead
              wherever possible.

       - count ?submodifier? chars
              Adjust the index backward by count characters, moving to earlier
              lines in the text if necessary. If there are fewer than count
              characters in the text before the current index, then set the
              index to the first index in the text (1.0). Spaces on either
              side of count are optional. If the display submodifier is given,
              elided characters are skipped over without being counted. If any
              is given, then all characters are counted. For historical
              reasons, if neither modifier is given then the count actually
              takes place in units of index positions (see INDICES for
              details). This behavior may be changed in a future major
              release, so if you need an index count, you are encouraged to
              use indices instead wherever possible.

       + count ?submodifier? indices
              Adjust the index forward by count index positions, moving to
              later lines in the text if necessary. If there are fewer than
              count index positions in the text after the current index, then
              set the index to the last index position in the text. Spaces on
              either side of count are optional. Note that an index position
              is either a single character or a single embedded image or
              embedded window. If the display submodifier is given, elided
              indices are skipped over without being counted. If any is given,
              then all indices are counted; this is also the default behaviour
              if no modifier is given.

       - count ?submodifier? indices
              Adjust the index backward by count index positions, moving to
              earlier lines in the text if necessary. If there are fewer than
              count index positions in the text before the current index, then
              set the index to the first index position (1.0) in the text.
              Spaces on either side of count are optional. If the display
              submodifier is given, elided indices are skipped over without
              being counted. If any is given, then all indices are counted;
              this is also the default behaviour if no modifier is given.

       + count ?submodifier? lines
              Adjust the index forward by count lines, retaining the same
              character position within the line. If there are fewer than
              count lines after the line containing the current index, then
              set the index to refer to the same character position on the
              last line of the text. Then, if the line is not long enough to
              contain a character at the indicated character position, adjust
              the character position to refer to the last character of the
              line (the newline).  Spaces on either side of count are
              optional. If the display submodifier is given, then each visual
              display line is counted separately.  Otherwise, if any (or no
              modifier) is given, then each logical line (no matter how many
              times it is visually wrapped) counts just once. If the relevant
              lines are not wrapped, then these two methods of counting are
              equivalent.

       - count ?submodifier? lines
              Adjust the index backward by count logical lines, retaining the
              same character position within the line. If there are fewer than
              count lines before the line containing the current index, then
              set the index to refer to the same character position on the
              first line of the text. Then, if the line is not long enough to
              contain a character at the indicated character position, adjust
              the character position to refer to the last character of the
              line (the newline). Spaces on either side of count are optional.
              If the display submodifier is given, then each visual display
              line is counted separately. Otherwise, if any (or no modifier)
              is given, then each logical line (no matter how many times it is
              visually wrapped) counts just once. If the relevant lines are
              not wrapped, then these two methods of counting are equivalent.

       ?submodifier? linestart
              Adjust the index to refer to the first index on the line. If the
              display submodifier is given, this is the first index on the
              display line, otherwise on the logical line.

       ?submodifier? lineend
              Adjust the index to refer to the last index on the line (the
              newline). If the display submodifier is given, this is the last
              index on the display line, otherwise on the logical line.

       ?submodifier? wordstart
              Adjust the index to refer to the first character of the word
              containing the current index. A word consists of any number of
              adjacent characters that are letters, digits, or underscores, or
              a single character that is not one of these. If the display
              submodifier is given, this only examines non-elided characters,
              otherwise all characters (elided or not) are examined.

       ?submodifier? wordend
              Adjust the index to refer to the character just after the last
              one of the word containing the current index. If the current
              index refers to the last character of the text then it is not
              modified. If the display submodifier is given, this only
              examines non-elided characters, otherwise all characters (elided
              or not) are examined.

       If more than one modifier is present then they are applied in left-to-
       right order. For example, the index "end - 1 chars" refers to the next-
       to-last character in the text and "insert wordstart - 1 c" refers to
       the character just before the first one in the word containing the
       insertion cursor. Modifiers are applied one by one in this left to
       right order, and after each step the resulting index is constrained to
       be a valid index in the text widget. So, for example, the index "1.0
       -1c +1c" refers to the index "2.0".

       Where modifiers result in index changes by display lines, display chars
       or display indices, and the base refers to an index inside an elided
       tag, that base index is considered to be equivalent to the first
       following non-elided index.

TAGS
       The first form of annotation in text widgets is a tag. A tag is a
       textual string that is associated with some of the characters in a
       text. Tags may contain arbitrary characters, but it is probably best to
       avoid using the characters " " (space), +, or -: these characters have
       special meaning in indices, so tags containing them cannot be used as
       indices. There may be any number of tags associated with characters in
       a text. Each tag may refer to a single character, a range of
       characters, or several ranges of characters. An individual character
       may have any number of tags associated with it.

       A priority order is defined among tags, and this order is used in
       implementing some of the tag-related functions described below. When a
       tag is defined (by associating it with characters or setting its
       display options or binding commands to it), it is given a priority
       higher than any existing tag. The priority order of tags may be
       redefined using the "pathName tag raise" and "pathName tag lower"
       widget commands.

       Tags serve three purposes in text widgets. First, they control the way
       information is displayed on the screen. By default, characters are
       displayed as determined by the -background, -font, and -foreground
       options for the text widget. However, display options may be associated
       with individual tags using the "pathName tag configure" widget command.
       If a character has been tagged, then the display options associated
       with the tag override the default display style. The following options
       are currently supported for tags:

       -background color
              Color specifies the background color to use for characters
              associated with the tag. It may have any of the forms accepted
              by Tk_GetColor.

       -bgstipple bitmap
              Bitmap specifies a bitmap that is used as a stipple pattern for
              the background. It may have any of the forms accepted by
              Tk_GetBitmap. If bitmap has not been specified, or if it is
              specified as an empty string, then a solid fill will be used for
              the background.

       -borderwidth pixels
              Pixels specifies the width of a border to draw around the tag
              using any of the forms accepted by Tk_GetPixels. This option
              should be used in conjunction with the -relief option to provide
              the desired border.

       -elide boolean
              Elide specifies whether the data should be elided. Elided data
              (characters, images, embedded windows, etc.) is not displayed
              and takes no space on screen, but further on behaves just as
              normal data.

       -fgstipple bitmap
              Bitmap specifies a bitmap that is used as a stipple pattern when
              drawing text and other foreground information such as
              underlines. It may have any of the forms accepted by
              Tk_GetBitmap. If bitmap has not been specified, or if it is
              specified as an empty string, then a solid fill will be used.

       -font fontName
              FontName is the name of a font to use for drawing characters. It
              may have any of the forms accepted by Tk_GetFont.

       -foreground color
              Color specifies the color to use when drawing text and other
              foreground information such as underlines. It may have any of
              the forms accepted by Tk_GetColor.

       -justify justify
              If the first non-elided character of a display line has a tag
              for which this option has been specified, then justify
              determines how to justify the line. It must be one of left,
              right, or center. If a line wraps, then the justification for
              each line on the display is determined by the first non-elided
              character of that display line.

       -lmargin1 pixels
              If the first non-elided character of a text line has a tag for
              which this option has been specified, then pixels specifies how
              much the line should be indented from the left edge of the
              window. Pixels may have any of the standard forms for screen
              distances. If a line of text wraps, this option only applies to
              the first line on the display; the -lmargin2 option controls the
              indentation for subsequent lines.

       -lmargin2 pixels
              If the first non-elided character of a display line has a tag
              for which this option has been specified, and if the display
              line is not the first for its text line (i.e., the text line has
              wrapped), then pixels specifies how much the line should be
              indented from the left edge of the window.  Pixels may have any
              of the standard forms for screen distances. This option is only
              used when wrapping is enabled, and it only applies to the second
              and later display lines for a text line.

       -offset pixels
              Pixels specifies an amount by which the text's baseline should
              be offset vertically from the baseline of the overall line, in
              pixels. For example, a positive offset can be used for
              superscripts and a negative offset can be used for subscripts.
              Pixels may have any of the standard forms for screen distances.

       -overstrike boolean
              Specifies whether or not to draw a horizontal rule through the
              middle of characters. Boolean may have any of the forms accepted
              by Tcl_GetBoolean.

       -relief relief
              Relief specifies the relief style to use for drawing the border,
              in any of the forms accepted by Tk_GetRelief. This option is
              used in conjunction with the -borderwidth option to enable to
              the desired border appearance.

       -rmargin pixels
              If the first non-elided character of a display line has a tag
              for which this option has been specified, then pixels specifies
              how wide a margin to leave between the end of the line and the
              right edge of the window.  Pixels may have any of the standard
              forms for screen distances. This option is only used when
              wrapping is enabled. If a text line wraps, the right margin for
              each line on the display is determined by the first non-elided
              character of that display line.

       -spacing1 pixels
              Pixels specifies how much additional space should be left above
              each text line, using any of the standard forms for screen
              distances. If a line wraps, this option only applies to the
              first line on the display.

       -spacing2 pixels
              For lines that wrap, this option specifies how much additional
              space to leave between the display lines for a single text line.
              Pixels may have any of the standard forms for screen distances.

       -spacing3 pixels
              Pixels specifies how much additional space should be left below
              each text line, using any of the standard forms for screen
              distances. If a line wraps, this option only applies to the last
              line on the display.

       -tabs tabList
              TabList specifies a set of tab stops in the same form as for the
              -tabs option for the text widget. This option only applies to a
              display line if it applies to the first non-elided character on
              that display line. If this option is specified as an empty
              string, it cancels the option, leaving it unspecified for the
              tag (the default). If the option is specified as a non-empty
              string that is an empty list, such as -tags { }, then it
              requests default 8-character tabs as described for the -tags
              widget option.

       -tabstyle style
              Style specifies either the tabular or wordprocessor style of
              tabbing to use for the text widget. This option only applies to
              a display line if it applies to the first non-elided character
              on that display line. If this option is specified as an empty
              string, it cancels the option, leaving it unspecified for the
              tag (the default).

       -underline boolean
              Boolean specifies whether or not to draw an underline underneath
              characters. It may have any of the forms accepted by
              Tcl_GetBoolean.

       -wrap mode
              Mode specifies how to handle lines that are wider than the
              text's window. It has the same legal values as the -wrap option
              for the text widget: none, char, or word. If this tag option is
              specified, it overrides the -wrap option for the text widget.

       If a character has several tags associated with it, and if their
       display options conflict, then the options of the highest priority tag
       are used. If a particular display option has not been specified for a
       particular tag, or if it is specified as an empty string, then that
       option will never be used; the next-highest-priority tag's option will
       used instead. If no tag specifies a particular display option, then the
       default style for the widget will be used.

       The second purpose for tags is event bindings. You can associate
       bindings with a tag in much the same way you can associate bindings
       with a widget class: whenever particular X events occur on characters
       with the given tag, a given Tcl command will be executed. Tag bindings
       can be used to give behaviors to ranges of characters; among other
       things, this allows hypertext-like features to be implemented. For
       details, see the description of the "pathName tag bind" widget command
       below. Tag bindings are shared between all peer widgets (including any
       bindings for the special sel tag).

       The third use for tags is in managing the selection. See THE SELECTION
       below. With the exception of the special sel tag, all tags are shared
       between peer text widgets, and may be manipulated on an equal basis
       from any such widget. The sel tag exists separately and independently
       in each peer text widget (but any tag bindings to sel are shared).

MARKS
       The second form of annotation in text widgets is a mark. Marks are used
       for remembering particular places in a text. They are something like
       tags, in that they have names and they refer to places in the file, but
       a mark is not associated with particular characters. Instead, a mark is
       associated with the gap between two characters. Only a single position
       may be associated with a mark at any given time. If the characters
       around a mark are deleted the mark will still remain; it will just have
       new neighbor characters. In contrast, if the characters containing a
       tag are deleted then the tag will no longer have an association with
       characters in the file. Marks may be manipulated with the "pathName
       mark" widget command, and their current locations may be determined by
       using the mark name as an index in widget commands.

       Each mark also has a "gravity", which is either left or right. The
       gravity for a mark specifies what happens to the mark when text is
       inserted at the point of the mark. If a mark has left gravity, then the
       mark is treated as if it were attached to the character on its left, so
       the mark will remain to the left of any text inserted at the mark
       position. If the mark has right gravity, new text inserted at the mark
       position will appear to the left of the mark (so that the mark remains
       rightmost). The gravity for a mark defaults to right.

       The name space for marks is different from that for tags: the same name
       may be used for both a mark and a tag, but they will refer to different
       things.

       Two marks have special significance. First, the mark insert is
       associated with the insertion cursor, as described under THE INSERTION
       CURSOR below. Second, the mark current is associated with the character
       closest to the mouse and is adjusted automatically to track the mouse
       position and any changes to the text in the widget (one exception:
       current is not updated in response to mouse motions if a mouse button
       is down; the update will be deferred until all mouse buttons have been
       released).  Neither of these special marks may be deleted. With the
       exception of these two special marks, all marks are shared between peer
       text widgets, and may be manipulated on an equal basis from any peer.

EMBEDDED WINDOWS
       The third form of annotation in text widgets is an embedded window.
       Each embedded window annotation causes a window to be displayed at a
       particular point in the text. There may be any number of embedded
       windows in a text widget, and any widget may be used as an embedded
       window (subject to the usual rules for geometry management, which
       require the text window to be the parent of the embedded window or a
       descendant of its parent). The embedded window's position on the screen
       will be updated as the text is modified or scrolled, and it will be
       mapped and unmapped as it moves into and out of the visible area of the
       text widget. Each embedded window occupies one unit's worth of index
       space in the text widget, and it may be referred to either by the name
       of its embedded window or by its position in the widget's index space.
       If the range of text containing the embedded window is deleted then the
       window is destroyed. Similarly if the text widget as a whole is
       deleted, then the window is destroyed.

       When an embedded window is added to a text widget with the pathName
       window create widget command, several configuration options may be
       associated with it. These options may be modified later with the
       pathName window configure widget command. The following options are
       currently supported:

       -align where
              If the window is not as tall as the line in which it is
              displayed, this option determines where the window is displayed
              in the line. Where must have one of the values top (align the
              top of the window with the top of the line), center (center the
              window within the range of the line), bottom (align the bottom
              of the window with the bottom of the line's area), or baseline
              (align the bottom of the window with the baseline of the line).

       -create script
              Specifies a Tcl script that may be evaluated to create the
              window for the annotation. If no -window option has been
              specified for the annotation this script will be evaluated when
              the annotation is about to be displayed on the screen. Script
              must create a window for the annotation and return the name of
              that window as its result. Two substitutions will be performed
              in script before evaluation. %W will be substituted by the name
              of the parent text widget, and %% will be substituted by a
              single %.  If the annotation's window should ever be deleted,
              script will be evaluated again the next time the annotation is
              displayed.

       -padx pixels
              Pixels specifies the amount of extra space to leave on each side
              of the embedded window. It may have any of the usual forms
              defined for a screen distance.

       -pady pixels
              Pixels specifies the amount of extra space to leave on the top
              and on the bottom of the embedded window. It may have any of the
              usual forms defined for a screen distance.

       -stretch boolean
              If the requested height of the embedded window is less than the
              height of the line in which it is displayed, this option can be
              used to specify whether the window should be stretched
              vertically to fill its line. If the -pady option has been
              specified as well, then the requested padding will be retained
              even if the window is stretched.

       -window pathName
              Specifies the name of a window to display in the annotation.
              Note that if a pathName has been set, then later configuring a
              window to the empty string will not delete the widget
              corresponding to the old pathName.  Rather it will remove the
              association between the old pathName and the text widget. If
              multiple peer widgets are in use, it is usually simpler to use
              the -create option if embedded windows are desired in each peer.

EMBEDDED IMAGES
       The final form of annotation in text widgets is an embedded image. Each
       embedded image annotation causes an image to be displayed at a
       particular point in the text. There may be any number of embedded
       images in a text widget, and a particular image may be embedded in
       multiple places in the same text widget. The embedded image's position
       on the screen will be updated as the text is modified or scrolled. Each
       embedded image occupies one unit's worth of index space in the text
       widget, and it may be referred to either by its position in the
       widget's index space, or the name it is assigned when the image is
       inserted into the text widget with pathName image create. If the range
       of text containing the embedded image is deleted then that copy of the
       image is removed from the screen.

       When an embedded image is added to a text widget with the pathName
       image create widget command, a name unique to this instance of the
       image is returned. This name may then be used to refer to this image
       instance. The name is taken to be the value of the -name option
       (described below). If the -name option is not provided, the -image name
       is used instead.  If the imageName is already in use in the text
       widget, then #nn is added to the end of the imageName, where nn is an
       arbitrary integer. This insures the imageName is unique. Once this name
       is assigned to this instance of the image, it does not change, even
       though the -image or -name values can be changed with pathName image
       configure.

       When an embedded image is added to a text widget with the pathName
       image create widget command, several configuration options may be
       associated with it. These options may be modified later with the
       pathName image configure widget command. The following options are
       currently supported:

       -align where
              If the image is not as tall as the line in which it is
              displayed, this option determines where the image is displayed
              in the line. Where must have one of the values top (align the
              top of the image with the top of the line), center (center the
              image within the range of the line), bottom (align the bottom of
              the image with the bottom of the line's area), or baseline
              (align the bottom of the image with the baseline of the line).

       -image image
              Specifies the name of the Tk image to display in the annotation.
              If image is not a valid Tk image, then an error is returned.

       -name ImageName
              Specifies the name by which this image instance may be
              referenced in the text widget. If ImageName is not supplied,
              then the name of the Tk image is used instead. If the imageName
              is already in use, #nn is appended to the end of the name as
              described above.

       -padx pixels
              Pixels specifies the amount of extra space to leave on each side
              of the embedded image. It may have any of the usual forms
              defined for a screen distance.

       -pady pixels
              Pixels specifies the amount of extra space to leave on the top
              and on the bottom of the embedded image. It may have any of the
              usual forms defined for a screen distance.

THE SELECTION
       Selection support is implemented via tags. If the -exportselection
       option for the text widget is true then the sel tag will be associated
       with the selection:

       [1]    Whenever characters are tagged with sel the text widget will
              claim ownership of the selection.

       [2]    Attempts to retrieve the selection will be serviced by the text
              widget, returning all the characters with the sel tag.

       [3]    If the selection is claimed away by another application or by
              another window within this application, then the sel tag will be
              removed from all characters in the text.

       [4]    Whenever the sel tag range changes a virtual event <<Selection>>
              is generated.

       The sel tag is automatically defined when a text widget is created, and
       it may not be deleted with the "pathName tag delete" widget command.
       Furthermore, the -selectbackground, -selectborderwidth, and
       -selectforeground options for the text widget are tied to the
       -background, -borderwidth, and -foreground options for the sel tag:
       changes in either will automatically be reflected in the other. Also
       the -inactiveselectbackground option for the text widget is used
       instead of -selectbackground when the text widget does not have the
       focus. This allows programmatic control over the visualization of the
       sel tag for foreground and background windows, or to have sel not shown
       at all (when -inactiveselectbackground is empty) for background
       windows. Each peer text widget has its own sel tag which can be
       separately configured and set.

THE INSERTION CURSOR
       The mark named insert has special significance in text widgets. It is
       defined automatically when a text widget is created and it may not be
       unset with the "pathName mark unset" widget command. The insert mark
       represents the position of the insertion cursor, and the insertion
       cursor will automatically be drawn at this point whenever the text
       widget has the input focus.

THE MODIFIED FLAG
       The text widget can keep track of changes to the content of the widget
       by means of the modified flag. Inserting or deleting text will set this
       flag. The flag can be queried, set and cleared programmatically as
       well. Whenever the flag changes state a <<Modified>> virtual event is
       generated. See the pathName edit modified widget command for more
       details.

THE UNDO MECHANISM
       The text widget has an unlimited undo and redo mechanism (when the
       -undo widget option is true) which records every insert and delete
       action on a stack.

       Boundaries (called "separators") are inserted between edit actions. The
       purpose of these separators is to group inserts, deletes and replaces
       into one compound edit action. When undoing a change everything between
       two separators will be undone. The undone changes are then moved to the
       redo stack, so that an undone edit can be redone again.  The redo stack
       is cleared whenever new edit actions are recorded on the undo stack.
       The undo and redo stacks can be cleared to keep their depth under
       control.

       Separators are inserted automatically when the -autoseparators widget
       option is true. You can insert separators programmatically as well. If
       a separator is already present at the top of the undo stack no other
       will be inserted. That means that two separators on the undo stack are
       always separated by at least one insert or delete action.

       The undo mechanism is also linked to the modified flag. This means that
       undoing or redoing changes can take a modified text widget back to the
       unmodified state or vice versa. The modified flag will be set
       automatically to the appropriate state. This automatic coupling does
       not work when the modified flag has been set by the user, until the
       flag has been reset again.

       See below for the pathName edit widget command that controls the undo
       mechanism.

PEER WIDGETS
       The text widget has a separate store of all its data concerning each
       line's textual contents, marks, tags, images and windows, and the undo
       stack.

       While this data store cannot be accessed directly (i.e. without a text
       widget as an intermediary), multiple text widgets can be created, each
       of which present different views on the same underlying data. Such text
       widgets are known as peer text widgets.

       As text is added, deleted, edited and coloured in any one widget, and
       as images, marks, tags are adjusted, all such changes will be reflected
       in all peers.

       All data and markup is shared, except for a few small details. First,
       the sel tag may be set and configured (in its display style)
       differently for each peer. Second, each peer has its own insert and
       current mark positions (but all other marks are shared). Third,
       embedded windows, which are arbitrary other widgets, cannot be shared
       between peers. This means the -window option of embedded windows is
       independently set for each peer (it is advisable to use the -create
       script capabilities to allow each peer to create its own embedded
       windows as needed). Fourth, all of the configuration options of each
       peer (e.g. -font, etc) can be set independently, with the exception of
       -undo, -maxundo, -autoseparators (i.e. all undo, redo and modified
       state issues are shared).

       Finally any single peer need not contain all lines from the underlying
       data store. When creating a peer, a contiguous range of lines (e.g.
       only lines 52 through 125) may be specified. This allows a peer to
       contain just a small portion of the overall text. The range of lines
       will expand and contract as text is inserted or deleted. The peer will
       only ever display complete lines of text (one cannot share just part of
       a line). If the peer's contents contracts to nothing (i.e. all complete
       lines in the peer widget have been deleted from another widget), then
       it is impossible for new lines to be inserted. The peer will simply
       become an empty shell on which the background can be configured, but
       which will never show any content (without manual reconfiguration of
       the start and end lines). Note that a peer which does not contain all
       of the underlying data store still has indices numbered from "1.0" to
       "end".  It is simply that those indices reflect a subset of the total
       data, and data outside the contained range is not accessible to the
       peer. This means that the command peerName index end may return quite
       different values in different peers. Similarly, commands like peerName
       tag ranges will not return index ranges outside that which is
       meaningful to the peer. The configuration options -startline and
       -endline may be used to control how much of the underlying data is
       contained in any given text widget.

       Note that peers are really peers. Deleting the "original" text widget
       will not cause any other peers to be deleted, or otherwise affected.

       See below for the pathName peer widget command that controls the
       creation of peer widgets.

WIDGET COMMAND
       The text command creates a new Tcl command whose name is the same as
       the path name of the text's window. This command may be used to invoke
       various operations on the widget. It has the following general form:
              pathName option ?arg arg ...?
       PathName is the name of the command, which is the same as the text
       widget's path name. Option and the args determine the exact behavior of
       the command. The following commands are possible for text widgets:

       pathName bbox index
              Returns a list of four elements describing the screen area of
              the character given by index. The first two elements of the list
              give the x and y coordinates of the upper-left corner of the
              area occupied by the character, and the last two elements give
              the width and height of the area. If the character is only
              partially visible on the screen, then the return value reflects
              just the visible part. If the character is not visible on the
              screen then the return value is an empty list.

       pathName cget option
              Returns the current value of the configuration option given by
              option.  Option may have any of the values accepted by the text
              command.

       pathName compare index1 op index2
              Compares the indices given by index1 and index2 according to the
              relational operator given by op, and returns 1 if the
              relationship is satisfied and 0 if it is not. Op must be one of
              the operators <, <=, ==, >=, >, or !=. If op is == then 1 is
              returned if the two indices refer to the same character, if op
              is < then 1 is returned if index1 refers to an earlier character
              in the text than index2, and so on.

       pathName configure ?option? ?value option value ...?
              Query or modify the configuration options of the widget. If no
              option is specified, returns a list describing all of the
              available options for pathName (see Tk_ConfigureInfo for
              information on the format of this list). If option is specified
              with no value, then the command returns a list describing the
              one named option (this list will be identical to the
              corresponding sublist of the value returned if no option is
              specified). If one or more option-value pairs are specified,
              then the command modifies the given widget option(s) to have the
              given value(s); in this case the command returns an empty
              string. Option may have any of the values accepted by the text
              command.

       pathName count ?options? index1 index2
              Counts the number of relevant things between the two indices. If
              index1 is after index2, the result will be a negative number
              (and this holds for each of the possible options). The actual
              items which are counted depend on the options given. The result
              is a list of integers, one for the result of each counting
              option given. Valid counting options are -chars, -displaychars,
              -displayindices, -displaylines, -indices, -lines, -xpixels and
              -ypixels. The default value, if no option is specified, is
              -indices. There is an additional possible option -update which
              is a modifier. If given, then all subsequent options ensure that
              any possible out of date information is recalculated. This
              currently only has any effect for the -ypixels count (which, if
              -update is not given, will use the text widget's current cached
              value for each line). The count options are interpreted as
              follows:

              -chars count all characters, whether elided or not. Do not count
                     embedded windows or images.

              -displaychars
                     count all non-elided characters.

              -displayindices
                     count all non-elided characters, windows and images.

              -displaylines
                     count all display lines (i.e. counting one for each time
                     a line wraps) from the line of the first index up to, but
                     not including the display line of the second index.
                     Therefore if they are both on the same display line, zero
                     will be returned. By definition displaylines are visible
                     and therefore this only counts portions of actual visible
                     lines.

              -indices
                     count all characters and embedded windows or images (i.e.
                     everything which counts in text-widget index space),
                     whether they are elided or not.

              -lines count all logical lines (irrespective of wrapping) from
                     the line of the first index up to, but not including the
                     line of the second index. Therefore if they are both on
                     the same line, zero will be returned. Logical lines are
                     counted whether they are currently visible (non-elided)
                     or not.

              -xpixels
                     count the number of horizontal pixels from the first
                     pixel of the first index to (but not including) the first
                     pixel of the second index. To count the total desired
                     width of the text widget (assuming wrapping is not
                     enabled), first find the longest line and then use ".text
                     count -xpixels "${line}.0" "${line}.0 lineend"".

              -ypixels
                     count the number of vertical pixels from the first pixel
                     of the first index to (but not including) the first pixel
                     of the second index. If both indices are on the same
                     display line, zero will be returned. To count the total
                     number of vertical pixels in the text widget, use ".text
                     count -ypixels 1.0 end", and to ensure this is up to
                     date, use ".text count -update -ypixels 1.0 end".

              The command returns a positive or negative integer corresponding
              to the number of items counted between the two indices. One such
              integer is returned for each counting option given, so a list is
              returned if more than one option was supplied. For example
              ".text count -xpixels -ypixels 1.3 4.5" is perfectly valid and
              will return a list of two elements.

       pathName debug ?boolean?
              If boolean is specified, then it must have one of the true or
              false values accepted by Tcl_GetBoolean. If the value is a true
              one then internal consistency checks will be turned on in the B-
              tree code associated with text widgets. If boolean has a false
              value then the debugging checks will be turned off. In either
              case the command returns an empty string. If boolean is not
              specified then the command returns on or off to indicate whether
              or not debugging is turned on. There is a single debugging
              switch shared by all text widgets: turning debugging on or off
              in any widget turns it on or off for all widgets. For widgets
              with large amounts of text, the consistency checks may cause a
              noticeable slow-down.

              When debugging is turned on, the drawing routines of the text
              widget set the global variables tk_textRedraw and
              tk_textRelayout to the lists of indices that are redrawn. The
              values of these variables are tested by Tk's test suite.

       pathName delete index1 ?index2 ...?
              Delete a range of characters from the text. If both index1 and
              index2 are specified, then delete all the characters starting
              with the one given by index1 and stopping just before index2
              (i.e. the character at index2 is not deleted). If index2 does
              not specify a position later in the text than index1 then no
              characters are deleted.  If index2 is not specified then the
              single character at index1 is deleted. It is not allowable to
              delete characters in a way that would leave the text without a
              newline as the last character. The command returns an empty
              string. If more indices are given, multiple ranges of text will
              be deleted.  All indices are first checked for validity before
              any deletions are made. They are sorted and the text is removed
              from the last range to the first range so deleted text does not
              cause an undesired index shifting side-effects. If multiple
              ranges with the same start index are given, then the longest
              range is used. If overlapping ranges are given, then they will
              be merged into spans that do not cause deletion of text outside
              the given ranges due to text shifted during deletion.

       pathName dlineinfo index
              Returns a list with five elements describing the area occupied
              by the display line containing index. The first two elements of
              the list give the x and y coordinates of the upper-left corner
              of the area occupied by the line, the third and fourth elements
              give the width and height of the area, and the fifth element
              gives the position of the baseline for the line, measured down
              from the top of the area. All of this information is measured in
              pixels. If the current wrap mode is none and the line extends
              beyond the boundaries of the window, the area returned reflects
              the entire area of the line, including the portions that are out
              of the window. If the line is shorter than the full width of the
              window then the area returned reflects just the portion of the
              line that is occupied by characters and embedded windows. If the
              display line containing index is not visible on the screen then
              the return value is an empty list.

       pathName dump ?switches? index1 ?index2?
              Return the contents of the text widget from index1 up to, but
              not including index2, including the text and information about
              marks, tags, and embedded windows. If index2 is not specified,
              then it defaults to one character past index1. The information
              is returned in the following format:

              key1 value1 index1 key2 value2 index2 ...

              The possible key values are text, mark, tagon, tagoff, image,
              and window. The corresponding value is the text, mark name, tag
              name, image name, or window name. The index information is the
              index of the start of the text, mark, tag transition, image or
              window. One or more of the following switches (or abbreviations
              thereof) may be specified to control the dump:

              -all   Return information about all elements: text, marks, tags,
                     images and windows.  This is the default.

              -command command
                     Instead of returning the information as the result of the
                     dump operation, invoke the command on each element of the
                     text widget within the range.  The command has three
                     arguments appended to it before it is evaluated: the key,
                     value, and index.

              -image Include information about images in the dump results.

              -mark  Include information about marks in the dump results.

              -tag   Include information about tag transitions in the dump
                     results. Tag information is returned as tagon and tagoff
                     elements that indicate the begin and end of each range of
                     each tag, respectively.

              -text  Include information about text in the dump results. The
                     value is the text up to the next element or the end of
                     range indicated by index2. A text element does not span
                     newlines. A multi-line block of text that contains no
                     marks or tag transitions will still be dumped as a set of
                     text segments that each end with a newline. The newline
                     is part of the value.

              -window
                     Include information about embedded windows in the dump
                     results. The value of a window is its Tk pathname, unless
                     the window has not been created yet. (It must have a
                     create script.) In this case an empty string is returned,
                     and you must query the window by its index position to
                     get more information.

       pathName edit option ?arg arg ...?
              This command controls the undo mechanism and the modified flag.
              The exact behavior of the command depends on the option argument
              that follows the edit argument. The following forms of the
              command are currently supported:

              pathName edit modified ?boolean?
                     If boolean is not specified, returns the modified flag of
                     the widget.  The insert, delete, edit undo and edit redo
                     commands or the user can set or clear the modified flag.
                     If boolean is specified, sets the modified flag of the
                     widget to boolean.

              pathName edit redo
                     When the -undo option is true, reapplies the last undone
                     edits provided no other edits were done since then.
                     Generates an error when the redo stack is empty. Does
                     nothing when the -undo option is false.

              pathName edit reset
                     Clears the undo and redo stacks.

              pathName edit separator
                     Inserts a separator (boundary) on the undo stack. Does
                     nothing when the -undo option is false.

              pathName edit undo
                     Undoes the last edit action when the -undo option is
                     true. An edit action is defined as all the insert and
                     delete commands that are recorded on the undo stack in
                     between two separators. Generates an error when the undo
                     stack is empty. Does nothing when the -undo option is
                     false.

       pathName get ?-displaychars? ?--? index1 ?index2 ...?
              Return a range of characters from the text. The return value
              will be all the characters in the text starting with the one
              whose index is index1 and ending just before the one whose index
              is index2 (the character at index2 will not be returned). If
              index2 is omitted then the single character at index1 is
              returned. If there are no characters in the specified range
              (e.g. index1 is past the end of the file or index2 is less than
              or equal to index1) then an empty string is returned. If the
              specified range contains embedded windows, no information about
              them is included in the returned string. If multiple index pairs
              are given, multiple ranges of text will be returned in a list.
              Invalid ranges will not be represented with empty strings in the
              list. The ranges are returned in the order passed to pathName
              get. If the -displaychars option is given, then, within each
              range, only those characters which are not elided will be
              returned. This may have the effect that some of the returned
              ranges are empty strings.

       pathName image option ?arg arg ...?
              This command is used to manipulate embedded images. The behavior
              of the command depends on the option argument that follows the
              tag argument. The following forms of the command are currently
              supported:

              pathName image cget index option
                     Returns the value of a configuration option for an
                     embedded image. Index identifies the embedded image, and
                     option specifies a particular configuration option, which
                     must be one of the ones listed in the section EMBEDDED
                     IMAGES.

              pathName image configure index ?option value ...?
                     Query or modify the configuration options for an embedded
                     image. If no option is specified, returns a list
                     describing all of the available options for the embedded
                     image at index (see Tk_ConfigureInfo for information on
                     the format of this list). If option is specified with no
                     value, then the command returns a list describing the one
                     named option (this list will be identical to the
                     corresponding sublist of the value returned if no option
                     is specified). If one or more option-value pairs are
                     specified, then the command modifies the given option(s)
                     to have the given value(s); in this case the command
                     returns an empty string. See EMBEDDED IMAGES for
                     information on the options that are supported.

              pathName image create index ?option value ...?
                     This command creates a new image annotation, which will
                     appear in the text at the position given by index. Any
                     number of option-value pairs may be specified to
                     configure the annotation. Returns a unique identifier
                     that may be used as an index to refer to this image. See
                     EMBEDDED IMAGES for information on the options that are
                     supported, and a description of the identifier returned.

              pathName image names
                     Returns a list whose elements are the names of all image
                     instances currently embedded in window.

       pathName index index
              Returns the position corresponding to index in the form
              line.char where line is the line number and char is the
              character number.  Index may have any of the forms described
              under INDICES above.

       pathName insert index chars ?tagList chars tagList ...?
              Inserts all of the chars arguments just before the character at
              index. If index refers to the end of the text (the character
              after the last newline) then the new text is inserted just
              before the last newline instead. If there is a single chars
              argument and no tagList, then the new text will receive any tags
              that are present on both the character before and the character
              after the insertion point; if a tag is present on only one of
              these characters then it will not be applied to the new text. If
              tagList is specified then it consists of a list of tag names;
              the new characters will receive all of the tags in this list and
              no others, regardless of the tags present around the insertion
              point. If multiple chars-tagList argument pairs are present,
              they produce the same effect as if a separate pathName insert
              widget command had been issued for each pair, in order. The last
              tagList argument may be omitted.

       pathName mark option ?arg arg ...?
              This command is used to manipulate marks. The exact behavior of
              the command depends on the option argument that follows the mark
              argument. The following forms of the command are currently
              supported:

              pathName mark gravity markName ?direction?
                     If direction is not specified, returns left or right to
                     indicate which of its adjacent characters markName is
                     attached to. If direction is specified, it must be left
                     or right; the gravity of markName is set to the given
                     value.

              pathName mark names
                     Returns a list whose elements are the names of all the
                     marks that are currently set.

              pathName mark next index
                     Returns the name of the next mark at or after index. If
                     index is specified in numerical form, then the search for
                     the next mark begins at that index. If index is the name
                     of a mark, then the search for the next mark begins
                     immediately after that mark. This can still return a mark
                     at the same position if there are multiple marks at the
                     same index. These semantics mean that the mark next
                     operation can be used to step through all the marks in a
                     text widget in the same order as the mark information
                     returned by the pathName dump operation. If a mark has
                     been set to the special end index, then it appears to be
                     after end with respect to the pathName mark next
                     operation. An empty string is returned if there are no
                     marks after index.

              pathName mark previous index
                     Returns the name of the mark at or before index. If index
                     is specified in numerical form, then the search for the
                     previous mark begins with the character just before that
                     index. If index is the name of a mark, then the search
                     for the next mark begins immediately before that mark.
                     This can still return a mark at the same position if
                     there are multiple marks at the same index. These
                     semantics mean that the pathName mark previous operation
                     can be used to step through all the marks in a text
                     widget in the reverse order as the mark information
                     returned by the pathName dump operation. An empty string
                     is returned if there are no marks before index.

              pathName mark set markName index
                     Sets the mark named markName to a position just before
                     the character at index. If markName already exists, it is
                     moved from its old position; if it does not exist, a new
                     mark is created. This command returns an empty string.

              pathName mark unset markName ?markName markName ...?
                     Remove the mark corresponding to each of the markName
                     arguments. The removed marks will not be usable in
                     indices and will not be returned by future calls to
                     "pathName mark names".  This command returns an empty
                     string.

       pathName peer option args
              This command is used to create and query widget peers. It has
              two forms, depending on option:

              pathName peer create newPathName ?options?
                     Creates a peer text widget with the given newPathName,
                     and any optional standard configuration options (as for
                     the text command). By default the peer will have the same
                     start and end line as the parent widget, but these can be
                     overridden with the standard configuration options.

              pathName peer names
                     Returns a list of peers of this widget (this does not
                     include the widget itself). The order within this list is
                     undefined.

       pathName replace index1 index2 chars ?tagList chars tagList ...?
              Replaces the range of characters between index1 and index2 with
              the given characters and tags. See the section on pathName
              insert for an explanation of the handling of the tagList...
              arguments, and the section on pathName delete for an explanation
              of the handling of the indices. If index2 corresponds to an
              index earlier in the text than index1, an error will be
              generated.

              The deletion and insertion are arranged so that no unnecessary
              scrolling of the window or movement of insertion cursor occurs.
              In addition the undo/redo stack are correctly modified, if undo
              operations are active in the text widget. The command returns an
              empty string.

       pathName scan option args
              This command is used to implement scanning on texts. It has two
              forms, depending on option:

              pathName scan mark x y
                     Records x and y and the current view in the text window,
                     for use in conjunction with later pathName scan dragto
                     commands. Typically this command is associated with a
                     mouse button press in the widget. It returns an empty
                     string.

              pathName scan dragto x y
                     This command computes the difference between its x and y
                     arguments and the x and y arguments to the last pathName
                     scan mark command for the widget. It then adjusts the
                     view by 10 times the difference in coordinates. This
                     command is typically associated with mouse motion events
                     in the widget, to produce the effect of dragging the text
                     at high speed through the window. The return value is an
                     empty string.

       pathName search ?switches? pattern index ?stopIndex?
              Searches the text in pathName starting at index for a range of
              characters that matches pattern. If a match is found, the index
              of the first character in the match is returned as result;
              otherwise an empty string is returned. One or more of the
              following switches (or abbreviations thereof) may be specified
              to control the search:

              -forwards
                     The search will proceed forward through the text, finding
                     the first matching range starting at or after the
                     position given by index. This is the default.

              -backwards
                     The search will proceed backward through the text,
                     finding the matching range closest to index whose first
                     character is before index (it is not allowed to be at
                     index). Note that, for a variety of reasons, backwards
                     searches can be substantially slower than forwards
                     searches (particularly when using -regexp), so it is
                     recommended that performance-critical code use forward
                     searches.

              -exact Use exact matching: the characters in the matching range
                     must be identical to those in pattern. This is the
                     default.

              -regexp
                     Treat pattern as a regular expression and match it
                     against the text using the rules for regular expressions
                     (see the regexp command and the re_syntax page for
                     details). The default matching automatically passes both
                     the -lineanchor and -linestop options to the regexp
                     engine (unless -nolinestop is used), so that ^$ match
                     beginning and end of line, and ., [^ sequences will never
                     match the newline character \n.

              -nolinestop
                     This allows . and [^ sequences to match the newline
                     character \n, which they will otherwise not do (see the
                     regexp command for details). This option is only
                     meaningful if -regexp is also given, and an error will be
                     thrown otherwise. For example, to match the entire text,
                     use "pathName search -nolinestop -regexp ".*" 1.0".

              -nocase
                     Ignore case differences between the pattern and the text.

              -count varName
                     The argument following -count gives the name of a
                     variable; if a match is found, the number of index
                     positions between beginning and end of the matching range
                     will be stored in the variable. If there are no embedded
                     images or windows in the matching range (and there are no
                     elided characters if -elide is not given), this is
                     equivalent to the number of characters matched. In either
                     case, the range matchIdx to matchIdx + $count chars will
                     return the entire matched text.

              -all   Find all matches in the given range and return a list of
                     the indices of the first character of each match. If a
                     -count varName switch is given, then varName is also set
                     to a list containing one element for each successful
                     match. Note that, even for exact searches, the elements
                     of this list may be different, if there are embedded
                     images, windows or hidden text.  Searches with -all
                     behave very similarly to the Tcl command regexp -all, in
                     that overlapping matches are not normally returned. For
                     example, applying an -all search of the pattern "\w+"
                     against "hello there" will just match twice, once for
                     each word, and matching "Z[a-z]+Z" against "ZooZooZoo"
                     will just match once.

              -overlap
                     When performing -all searches, the normal behaviour is
                     that matches which overlap an already-found match will
                     not be returned. This switch changes that behaviour so
                     that all matches which are not totally enclosed within
                     another match are returned. For example, applying an
                     -overlap search of the pattern "\w+" against "hello
                     there" will just match twice (i.e. no different to just
                     -all), but matching "Z[a-z]+Z" against "ZooZooZoo" will
                     now match twice. An error will be thrown if this switch
                     is used without -all.

              -strictlimits
                     When performing any search, the normal behaviour is that
                     the start and stop limits are checked with respect to the
                     start of the matching text. With the -strictlimits flag,
                     the entire matching range must lie inside the start and
                     stop limits specified for the match to be valid.

              -elide Find elided (hidden) text as well. By default only
                     displayed text is searched.

              --     This switch has no effect except to terminate the list of
                     switches: the next argument will be treated as pattern
                     even if it starts with -.

              The matching range may be within a single line of text, or run
              across multiple lines (if parts of the pattern can match a new-
              line). For regular expression matching one can use the various
              newline-matching features such as $ to match the end of a line,
              ^ to match the beginning of a line, and to control whether . is
              allowed to match a new-line. If stopIndex is specified, the
              search stops at that index: for forward searches, no match at or
              after stopIndex will be considered; for backward searches, no
              match earlier in the text than stopIndex will be considered. If
              stopIndex is omitted, the entire text will be searched: when the
              beginning or end of the text is reached, the search continues at
              the other end until the starting location is reached again; if
              stopIndex is specified, no wrap-around will occur. This means
              that, for example, if the search is -forwards but stopIndex is
              earlier in the text than startIndex, nothing will ever be found.
              See KNOWN BUGS below for a number of minor limitations of the
              pathName search command.

       pathName see index
              Adjusts the view in the window so that the character given by
              index is completely visible. If index is already visible then
              the command does nothing. If index is a short distance out of
              view, the command adjusts the view just enough to make index
              visible at the edge of the window.  If index is far out of view,
              then the command centers index in the window.

       pathName tag option ?arg arg ...?
              This command is used to manipulate tags. The exact behavior of
              the command depends on the option argument that follows the tag
              argument. The following forms of the command are currently
              supported:

              pathName tag add tagName index1 ?index2 index1 index2 ...?
                     Associate the tag tagName with all of the characters
                     starting with index1 and ending just before index2 (the
                     character at index2 is not tagged). A single command may
                     contain any number of index1-index2 pairs. If the last
                     index2 is omitted then the single character at index1 is
                     tagged. If there are no characters in the specified range
                     (e.g. index1 is past the end of the file or index2 is
                     less than or equal to index1) then the command has no
                     effect.

              pathName tag bind tagName ?sequence? ?script?
                     This command associates script with the tag given by
                     tagName.  Whenever the event sequence given by sequence
                     occurs for a character that has been tagged with tagName,
                     the script will be invoked. This widget command is
                     similar to the bind command except that it operates on
                     characters in a text rather than entire widgets. See the
                     bind manual entry for complete details on the syntax of
                     sequence and the substitutions performed on script before
                     invoking it. If all arguments are specified then a new
                     binding is created, replacing any existing binding for
                     the same sequence and tagName (if the first character of
                     script is "+" then script augments an existing binding
                     rather than replacing it). In this case the return value
                     is an empty string. If script is omitted then the command
                     returns the script associated with tagName and sequence
                     (an error occurs if there is no such binding). If both
                     script and sequence are omitted then the command returns
                     a list of all the sequences for which bindings have been
                     defined for tagName.

                     The only events for which bindings may be specified are
                     those related to the mouse and keyboard (such as Enter,
                     Leave, ButtonPress, Motion, and KeyPress) or virtual
                     events. Event bindings for a text widget use the current
                     mark described under MARKS above. An Enter event triggers
                     for a tag when the tag first becomes present on the
                     current character, and a Leave event triggers for a tag
                     when it ceases to be present on the current character.
                     Enter and Leave events can happen either because the
                     current mark moved or because the character at that
                     position changed. Note that these events are different
                     than Enter and Leave events for windows. Mouse and
                     keyboard events are directed to the current character. If
                     a virtual event is used in a binding, that binding can
                     trigger only if the virtual event is defined by an
                     underlying mouse-related or keyboard-related event.

                     It is possible for the current character to have multiple
                     tags, and for each of them to have a binding for a
                     particular event sequence. When this occurs, one binding
                     is invoked for each tag, in order from lowest-priority to
                     highest priority. If there are multiple matching bindings
                     for a single tag, then the most specific binding is
                     chosen (see the manual entry for the bind command for
                     details). continue and break commands within binding
                     scripts are processed in the same way as for bindings
                     created with the bind command.

                     If bindings are created for the widget as a whole using
                     the bind command, then those bindings will supplement the
                     tag bindings. The tag bindings will be invoked first,
                     followed by bindings for the window as a whole.

              pathName tag cget tagName option
                     This command returns the current value of the option
                     named option associated with the tag given by tagName.
                     Option may have any of the values accepted by the
                     pathName tag configure widget command.

              pathName tag configure tagName ?option? ?value? ?option value
              ...?
                     This command is similar to the pathName configure widget
                     command except that it modifies options associated with
                     the tag given by tagName instead of modifying options for
                     the overall text widget. If no option is specified, the
                     command returns a list describing all of the available
                     options for tagName (see Tk_ConfigureInfo for information
                     on the format of this list). If option is specified with
                     no value, then the command returns a list describing the
                     one named option (this list will be identical to the
                     corresponding sublist of the value returned if no option
                     is specified). If one or more option-value pairs are
                     specified, then the command modifies the given option(s)
                     to have the given value(s) in tagName; in this case the
                     command returns an empty string.  See TAGS above for
                     details on the options available for tags.

              pathName tag delete tagName ?tagName ...?
                     Deletes all tag information for each of the tagName
                     arguments. The command removes the tags from all
                     characters in the file and also deletes any other
                     information associated with the tags, such as bindings
                     and display information. The command returns an empty
                     string.

              pathName tag lower tagName ?belowThis?
                     Changes the priority of tag tagName so that it is just
                     lower in priority than the tag whose name is belowThis.
                     If belowThis is omitted, then tagName's priority is
                     changed to make it lowest priority of all tags.

              pathName tag names ?index?
                     Returns a list whose elements are the names of all the
                     tags that are active at the character position given by
                     index. If index is omitted, then the return value will
                     describe all of the tags that exist for the text (this
                     includes all tags that have been named in a "pathName
                     tag" widget command but have not been deleted by a
                     "pathName tag delete" widget command, even if no
                     characters are currently marked with the tag). The list
                     will be sorted in order from lowest priority to highest
                     priority.

              pathName tag nextrange tagName index1 ?index2?
                     This command searches the text for a range of characters
                     tagged with tagName where the first character of the
                     range is no earlier than the character at index1 and no
                     later than the character just before index2 (a range
                     starting at index2 will not be considered). If several
                     matching ranges exist, the first one is chosen. The
                     command's return value is a list containing two elements,
                     which are the index of the first character of the range
                     and the index of the character just after the last one in
                     the range. If no matching range is found then the return
                     value is an empty string. If index2 is not given then it
                     defaults to the end of the text.

              pathName tag prevrange tagName index1 ?index2?
                     This command searches the text for a range of characters
                     tagged with tagName where the first character of the
                     range is before the character at index1 and no earlier
                     than the character at index2 (a range starting at index2
                     will be considered). If several matching ranges exist,
                     the one closest to index1 is chosen. The command's return
                     value is a list containing two elements, which are the
                     index of the first character of the range and the index
                     of the character just after the last one in the range. If
                     no matching range is found then the return value is an
                     empty string.  If index2 is not given then it defaults to
                     the beginning of the text.

              pathName tag raise tagName ?aboveThis?
                     Changes the priority of tag tagName so that it is just
                     higher in priority than the tag whose name is aboveThis.
                     If aboveThis is omitted, then tagName's priority is
                     changed to make it highest priority of all tags.

              pathName tag ranges tagName
                     Returns a list describing all of the ranges of text that
                     have been tagged with tagName. The first two elements of
                     the list describe the first tagged range in the text, the
                     next two elements describe the second range, and so on.
                     The first element of each pair contains the index of the
                     first character of the range, and the second element of
                     the pair contains the index of the character just after
                     the last one in the range. If there are no characters
                     tagged with tag then an empty string is returned.

              pathName tag remove tagName index1 ?index2 index1 index2 ...?
                     Remove the tag tagName from all of the characters
                     starting at index1 and ending just before index2 (the
                     character at index2 is not affected). A single command
                     may contain any number of index1-index2 pairs. If the
                     last index2 is omitted then the tag is removed from the
                     single character at index1. If there are no characters in
                     the specified range (e.g. index1 is past the end of the
                     file or index2 is less than or equal to index1) then the
                     command has no effect. This command returns an empty
                     string.

       pathName window option ?arg arg ...?
              This command is used to manipulate embedded windows. The
              behavior of the command depends on the option argument that
              follows the window argument. The following forms of the command
              are currently supported:

              pathName window cget index option
                     Returns the value of a configuration option for an
                     embedded window.  Index identifies the embedded window,
                     and option specifies a particular configuration option,
                     which must be one of the ones listed in the section
                     EMBEDDED WINDOWS.

              pathName window configure index ?option value ...?
                     Query or modify the configuration options for an embedded
                     window. If no option is specified, returns a list
                     describing all of the available options for the embedded
                     window at index (see Tk_ConfigureInfo for information on
                     the format of this list). If option is specified with no
                     value, then the command returns a list describing the one
                     named option (this list will be identical to the
                     corresponding sublist of the value returned if no option
                     is specified). If one or more option-value pairs are
                     specified, then the command modifies the given option(s)
                     to have the given value(s); in this case the command
                     returns an empty string. See EMBEDDED WINDOWS for
                     information on the options that are supported.

              pathName window create index ?option value ...?
                     This command creates a new window annotation, which will
                     appear in the text at the position given by index. Any
                     number of option-value pairs may be specified to
                     configure the annotation. See EMBEDDED WINDOWS for
                     information on the options that are supported. Returns an
                     empty string.

              pathName window names
                     Returns a list whose elements are the names of all
                     windows currently embedded in window.

       pathName xview option args
              This command is used to query and change the horizontal position
              of the text in the widget's window. It can take any of the
              following forms:

              pathName xview
                     Returns a list containing two elements. Each element is a
                     real fraction between 0 and 1; together they describe the
                     portion of the document's horizontal span that is visible
                     in the window. For example, if the first element is .2
                     and the second element is .6, 20% of the text is off-
                     screen to the left, the middle 40% is visible in the
                     window, and 40% of the text is off-screen to the right.
                     The fractions refer only to the lines that are actually
                     visible in the window: if the lines in the window are all
                     very short, so that they are entirely visible, the
                     returned fractions will be 0 and 1, even if there are
                     other lines in the text that are much wider than the
                     window.  These are the same values passed to scrollbars
                     via the -xscrollcommand option.

              pathName xview moveto fraction
                     Adjusts the view in the window so that fraction of the
                     horizontal span of the text is off-screen to the left.
                     Fraction is a fraction between 0 and 1.

              pathName xview scroll number what
                     This command shifts the view in the window left or right
                     according to number and what. What must be units, pages
                     or pixels. If what is units or pages then number must be
                     an integer, otherwise number may be specified in any of
                     the forms acceptable to Tk_GetPixels, such as "2.0c" or
                     "1i" (the result is rounded to the nearest integer value.
                     If no units are given, pixels are assumed). If what is
                     units, the view adjusts left or right by number average-
                     width characters on the display; if it is pages then the
                     view adjusts by number screenfuls; if it is pixels then
                     the view adjusts by number pixels. If number is negative
                     then characters farther to the left become visible; if it
                     is positive then characters farther to the right become
                     visible.

       pathName yview ?args?
              This command is used to query and change the vertical position
              of the text in the widget's window. It can take any of the
              following forms:

              pathName yview
                     Returns a list containing two elements, both of which are
                     real fractions between 0 and 1. The first element gives
                     the position of the first visible pixel of the first
                     character (or image, etc) in the top line in the window,
                     relative to the text as a whole (0.5 means it is halfway
                     through the text, for example). The second element gives
                     the position of the first pixel just after the last
                     visible one in the bottom line of the window, relative to
                     the text as a whole. These are the same values passed to
                     scrollbars via the -yscrollcommand option.

              pathName yview moveto fraction
                     Adjusts the view in the window so that the pixel given by
                     fraction appears at the top of the top line of the
                     window. Fraction is a fraction between 0 and 1; 0
                     indicates the first pixel of the first character in the
                     text, 0.33 indicates the pixel that is one-third the way
                     through the text; and so on. Values close to 1 will
                     indicate values close to the last pixel in the text (1
                     actually refers to one pixel beyond the last pixel), but
                     in such cases the widget will never scroll beyond the
                     last pixel, and so a value of 1 will effectively be
                     rounded back to whatever fraction ensures the last pixel
                     is at the bottom of the window, and some other pixel is
                     at the top.

              pathName yview scroll number what
                     This command adjust the view in the window up or down
                     according to number and what. What must be units, pages
                     or pixels. If what is units or pages then number must be
                     an integer, otherwise number may be specified in any of
                     the forms acceptable to Tk_GetPixels, such as "2.0c" or
                     "1i" (the result is rounded to the nearest integer value.
                     If no units are given, pixels are assumed). If what is
                     units, the view adjusts up or down by number lines on the
                     display; if it is pages then the view adjusts by number
                     screenfuls; if it is pixels then the view adjusts by
                     number pixels. If number is negative then earlier
                     positions in the text become visible; if it is positive
                     then later positions in the text become visible.

              pathName yview ?-pickplace? index
                     Changes the view in the widget's window to make index
                     visible. If the -pickplace option is not specified then
                     index will appear at the top of the window. If -pickplace
                     is specified then the widget chooses where index appears
                     in the window:

                     [1]    If index is already visible somewhere in the
                            window then the command does nothing.

                     [2]    If index is only a few lines off-screen above the
                            window then it will be positioned at the top of
                            the window.

                     [3]    If index is only a few lines off-screen below the
                            window then it will be positioned at the bottom of
                            the window.

                     [4]    Otherwise, index will be centered in the window.

                     The -pickplace option has been obsoleted by the pathName
                     see widget command (pathName see handles both x- and y-
                     motion to make a location visible, whereas the -pickplace
                     mode only handles motion in y).

              pathName yview number
                     This command makes the first character on the line after
                     the one given by number visible at the top of the window.
                     Number must be an integer. This command used to be used
                     for scrolling, but now it is obsolete.

BINDINGS
       Tk automatically creates class bindings for texts that give them the
       following default behavior. In the descriptions below, "word" is
       dependent on the value of the tcl_wordchars variable. See tclvars(n).

       [1]    Clicking mouse button 1 positions the insertion cursor just
              before the character underneath the mouse cursor, sets the input
              focus to this widget, and clears any selection in the widget.
              Dragging with mouse button 1 strokes out a selection between the
              insertion cursor and the character under the mouse.

       [2]    Double-clicking with mouse button 1 selects the word under the
              mouse and positions the insertion cursor at the start of the
              word. Dragging after a double click will stroke out a selection
              consisting of whole words.

       [3]    Triple-clicking with mouse button 1 selects the line under the
              mouse and positions the insertion cursor at the start of the
              line. Dragging after a triple click will stroke out a selection
              consisting of whole lines.

       [4]    The ends of the selection can be adjusted by dragging with mouse
              button 1 while the Shift key is down; this will adjust the end
              of the selection that was nearest to the mouse cursor when
              button 1 was pressed. If the button is double-clicked before
              dragging then the selection will be adjusted in units of whole
              words; if it is triple-clicked then the selection will be
              adjusted in units of whole lines.

       [5]    Clicking mouse button 1 with the Control key down will
              reposition the insertion cursor without affecting the selection.

       [6]    If any normal printing characters are typed, they are inserted
              at the point of the insertion cursor.

       [7]    The view in the widget can be adjusted by dragging with mouse
              button 2. If mouse button 2 is clicked without moving the mouse,
              the selection is copied into the text at the position of the
              mouse cursor. The Insert key also inserts the selection, but at
              the position of the insertion cursor.

       [8]    If the mouse is dragged out of the widget while button 1 is
              pressed, the entry will automatically scroll to make more text
              visible (if there is more text off-screen on the side where the
              mouse left the window).

       [9]    The Left and Right keys move the insertion cursor one character
              to the left or right; they also clear any selection in the text.
              If Left or Right is typed with the Shift key down, then the
              insertion cursor moves and the selection is extended to include
              the new character. Control-Left and Control-Right move the
              insertion cursor by words, and Control-Shift-Left and Control-
              Shift-Right move the insertion cursor by words and also extend
              the selection. Control-b and Control-f behave the same as Left
              and Right, respectively. Meta-b and Meta-f behave the same as
              Control-Left and Control-Right, respectively.

       [10]   The Up and Down keys move the insertion cursor one line up or
              down and clear any selection in the text. If Up or Right is
              typed with the Shift key down, then the insertion cursor moves
              and the selection is extended to include the new character.
              Control-Up and Control-Down move the insertion cursor by
              paragraphs (groups of lines separated by blank lines), and
              Control-Shift-Up and Control-Shift-Down move the insertion
              cursor by paragraphs and also extend the selection. Control-p
              and Control-n behave the same as Up and Down, respectively.

       [11]   The Next and Prior keys move the insertion cursor forward or
              backwards by one screenful and clear any selection in the text.
              If the Shift key is held down while Next or Prior is typed, then
              the selection is extended to include the new character.

       [12]   Control-Next and Control-Prior scroll the view right or left by
              one page without moving the insertion cursor or affecting the
              selection.

       [13]   Home and Control-a move the insertion cursor to the beginning of
              its display line and clear any selection in the widget. Shift-
              Home moves the insertion cursor to the beginning of the display
              line and also extends the selection to that point.

       [14]   End and Control-e move the insertion cursor to the end of the
              display line and clear any selection in the widget. Shift-End
              moves the cursor to the end of the display line and extends the
              selection to that point.

       [15]   Control-Home and Meta-< move the insertion cursor to the
              beginning of the text and clear any selection in the widget.
              Control-Shift-Home moves the insertion cursor to the beginning
              of the text and also extends the selection to that point.

       [16]   Control-End and Meta-> move the insertion cursor to the end of
              the text and clear any selection in the widget. Control-Shift-
              End moves the cursor to the end of the text and extends the
              selection to that point.

       [17]   The Select key and Control-Space set the selection anchor to the
              position of the insertion cursor. They do not affect the current
              selection. Shift-Select and Control-Shift-Space adjust the
              selection to the current position of the insertion cursor,
              selecting from the anchor to the insertion cursor if there was
              not any selection previously.

       [18]   Control-/ selects the entire contents of the widget.

       [19]   Control-\ clears any selection in the widget.

       [20]   The F16 key (labelled Copy on many Sun workstations) or Meta-w
              copies the selection in the widget to the clipboard, if there is
              a selection. This action is carried out by the command
              tk_textCopy.

       [21]   The F20 key (labelled Cut on many Sun workstations) or Control-w
              copies the selection in the widget to the clipboard and deletes
              the selection. This action is carried out by the command
              tk_textCut. If there is no selection in the widget then these
              keys have no effect.

       [22]   The F18 key (labelled Paste on many Sun workstations) or
              Control-y inserts the contents of the clipboard at the position
              of the insertion cursor. This action is carried out by the
              command tk_textPaste.

       [23]   The Delete key deletes the selection, if there is one in the
              widget. If there is no selection, it deletes the character to
              the right of the insertion cursor.

       [24]   Backspace and Control-h delete the selection, if there is one in
              the widget.  If there is no selection, they delete the character
              to the left of the insertion cursor.

       [25]   Control-d deletes the character to the right of the insertion
              cursor.

       [26]   Meta-d deletes the word to the right of the insertion cursor.

       [27]   Control-k deletes from the insertion cursor to the end of its
              line; if the insertion cursor is already at the end of a line,
              then Control-k deletes the newline character.

       [28]   Control-o opens a new line by inserting a newline character in
              front of the insertion cursor without moving the insertion
              cursor.

       [29]   Meta-backspace and Meta-Delete delete the word to the left of
              the insertion cursor.

       [30]   Control-x deletes whatever is selected in the text widget after
              copying it to the clipboard.

       [31]   Control-t reverses the order of the two characters to the right
              of the insertion cursor.

       [32]   Control-z (and Control-underscore on UNIX when tk_strictMotif is
              true) undoes the last edit action if the -undo option is true.
              Does nothing otherwise.

       [33]   Control-Z (or Control-y on Windows) reapplies the last undone
              edit action if the -undo option is true. Does nothing otherwise.

       If the widget is disabled using the -state option, then its view can
       still be adjusted and text can still be selected, but no insertion
       cursor will be displayed and no text modifications will take place.

       The behavior of texts can be changed by defining new bindings for
       individual widgets or by redefining the class bindings.

KNOWN ISSUES
   ISSUES CONCERNING CHARS AND INDICES
       Before Tk 8.5, the widget used the string "chars" to refer to index
       positions (which included characters, embedded windows and embedded
       images). As of Tk 8.5 the text widget deals separately and correctly
       with "chars" and "indices".  For backwards compatibility, however, the
       index modifiers "+N chars" and "-N chars" continue to refer to indices.
       One must use any of the full forms "+N any chars" or "-N any chars"
       etc. to refer to actual character indices. This confusion may be fixed
       in a future release by making the widget correctly interpret "+N chars"
       as a synonym for "+N any chars".

   PERFORMANCE ISSUES
       Text widgets should run efficiently under a variety of conditions. The
       text widget uses about 2-3 bytes of main memory for each byte of text,
       so texts containing a megabyte or more should be practical on most
       workstations. Text is represented internally with a modified B-tree
       structure that makes operations relatively efficient even with large
       texts. Tags are included in the B-tree structure in a way that allows
       tags to span large ranges or have many disjoint smaller ranges without
       loss of efficiency. Marks are also implemented in a way that allows
       large numbers of marks. In most cases it is fine to have large numbers
       of unique tags, or a tag that has many distinct ranges.

       One performance problem can arise if you have hundreds or thousands of
       different tags that all have the following characteristics: the first
       and last ranges of each tag are near the beginning and end of the text,
       respectively, or a single tag range covers most of the text widget. The
       cost of adding and deleting tags like this is proportional to the
       number of other tags with the same properties. In contrast, there is no
       problem with having thousands of distinct tags if their overall ranges
       are localized and spread uniformly throughout the text.

       Very long text lines can be expensive, especially if they have many
       marks and tags within them.

       The display line with the insert cursor is redrawn each time the cursor
       blinks, which causes a steady stream of graphics traffic. Set the
       -insertofftime attribute to 0 avoid this.

   KNOWN BUGS
       The pathName search -regexp sub-command attempts to perform
       sophisticated regexp matching across multiple lines in an efficient
       fashion (since Tk 8.5), examining each line individually, and then in
       small groups of lines, whether searching forwards or backwards. Under
       certain conditions the search result might differ from that obtained by
       applying the same regexp to the entire text from the widget in one go.
       For example, when searching with a greedy regexp, the widget will
       continue to attempt to add extra lines to the match as long as one of
       two conditions are true: either Tcl's regexp library returns a code to
       indicate a longer match is possible (but there are known bugs in Tcl
       which mean this code is not always correctly returned); or if each
       extra line added results in at least a partial match with the pattern.
       This means in the case where the first extra line added results in no
       match and Tcl's regexp system returns the incorrect code and adding a
       second extra line would actually match, the text widget will return the
       wrong result. In practice this is a rare problem, but it can occur, for
       example:
              pack [text .t]
              .t insert 1.0 "aaaa\nbbbb\ncccc\nbbbb\naaaa\n"
              .t search -regexp -- {(a+|b+\nc+\nb+)+\na+} 1.0
       will not find a match when one exists of 19 characters starting from
       the first "b".

       Whenever one possible match is fully enclosed in another, the search
       command will attempt to ensure only the larger match is returned. When
       performing backwards regexp searches it is possible that Tcl will not
       always achieve this, in the case where a match is preceded by one or
       more short, non-overlapping matches, all of which are preceded by a
       large match which actually encompasses all of them. The search
       algorithm used by the widget does not look back arbitrarily far for a
       possible match which might cover large portions of the widget. For
       example:
              pack [text .t]
              .t insert 1.0 "aaaa\nbbbb\nbbbb\nbbbb\nbbbb\n"
              .t search -regexp -backward -- {b+\n|a+\n(b+\n)+} end
       matches at "5.0" when a true greedy match would match at "1.0".
       Similarly if we add -all to this case, it matches at all of "5.0",
       "4.0", "3.0" and "1.0", when really it should only match at "1.0" since
       that match encloses all the others.

SEE ALSO
       entry(n), scrollbar(n)

KEYWORDS
       text, widget, tkvars



Tk                                    8.5                              text(n)
