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bindtags(3tk) Tk Built-In Commands 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. 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







  

    4.0
    Tk