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 Button, 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 nearest 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 argument 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

KEYWORDS

       binding, event, tag

Tk                                                     4.0                                         bindtags(3tk)