bindtags(3tk)						       Tk Built-In Commands						     bindtags(3tk)

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NAME

       bindtags - Determine which bindings apply to a window, and order of evaluation

SYNOPSIS

       bindtags window ?tagList?
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DESCRIPTION

       When a binding is created with the bind command, it is associated either with a particular window such as .a.b.c, a class name such as But-
       ton, the keyword all, or any other string.  All of these forms are called binding tags.	Each window contains a list of binding	tags  that
       determine  how events are processed for the window.  When an event occurs in a window, it is applied to each of the window's tags in order:
       for each tag, the most specific binding that matches the given tag and event is executed.  See the bind command for more information on the
       matching process.

       By default, each window has four binding tags consisting of the name of the window, the window's class name, the name of the window's near-
       est toplevel ancestor, and all, in that order.  Toplevel windows have only three tags by default, since the toplevel name is  the  same	as
       that of the window.  The bindtags command allows the binding tags for a window to be read and modified.

       If bindtags is invoked with only one argument, then the current set of binding tags for window is returned as a list.  If the tagList argu-
       ment is specified to bindtags, then it must be a proper list; the tags for window are changed to the elements of the list.  The elements of
       tagList	may  be  arbitrary  strings;   however, any tag starting with a dot is treated as the name of a window;  if no window by that name
       exists at the time an event is processed, then the tag is ignored for that event.  The order of the  elements  in  tagList  determines  the
       order in which binding scripts are executed in response to events.  For example, the command
	      bindtags .b {all . Button .b}
       reverses  the  order  in which binding scripts will be evaluated for a button named .b so that all bindings are invoked first, following by
       bindings for .b's toplevel ("."), followed by class bindings, followed by bindings for .b.  If tagList is an empty list	then  the  binding
       tags for window are returned to the default state described above.

       The bindtags command may be used to introduce arbitrary additional binding tags for a window, or to remove standard tags.  For example, the
       command
	      bindtags .b {.b TrickyButton . all}
       replaces the Button tag for .b with TrickyButton.  This means that the default widget bindings for buttons, which are associated  with  the
       Button tag, will no longer apply to .b, but any bindings associated with TrickyButton (perhaps some new button behavior) will apply.

EXAMPLE

       If  you	have  a  set of nested frame widgets and you want events sent to a button widget to also be delivered to all the widgets up to the
       current toplevel (in contrast to Tk's default behavior, where events are not delivered to those intermediate windows) to make it easier	to
       have accelerators that are only active for part of a window, you could use a helper procedure like this to help set things up:
	      proc setupBindtagsForTreeDelivery {widget} {
		  set tags [list $widget [winfo class $widget]]
		  set w $widget
		  set t [winfo toplevel $w]
		  while {$w ne $t} {
		      set w [winfo parent $w]
		      lappend tags $w
		  }
		  lappend tags all
		  bindtags $widget $tags
	      }

SEE ALSO

       bind(3tk)

KEYWORDS

       binding, event, tag

Tk									4.0							     bindtags(3tk)