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



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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 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  win-dow's window's
       dow'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 arbi-trary arbitrary
       trary strings;  however, any tag starting with a dot is treated as the name of a window;  if no  win-dow window
       dow  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 bind-ings bindings
       ings 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 asso-ciated associated
       ciated 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(n)


KEYWORDS
       binding, event, tag



Tk                                                   4.0                                         bindtags(n)