bindtags(3Tk)

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

SYNOPSIS
     bindtags window ?tagList?


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.

     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.
SEE ALSO
     bind


KEYWORDS
     binding, event, tag