''[RS] 2003-02-17 - Tags, strings that represent groups of objects, are a powerful concept, used in Tk for [text] portions, [canvas] items, and for bindings in [bindtags]. Another use for tags, and their Tcl implementation, has been proposed by [Bryan Oakley] in [the comp.lang.tcl newsgroup]:''

It's fairly easy to code up yourself, and makes for a nice little 
programming exercise.

A variation of what I do looks roughly like this (off of the top of my 
head, not tested, YMMV, void where prohibited by law, do not operate 
heavy machinery while using, wait two hours before going swimming, not 
suitable for young children, etc)


     # some typical widgets...
     .menubar.editMenu add command -label Paste ...
     .popupMenu add command -label Paste ...
     button .toolbar.paste -text Paste ...

     # associate them with a symbolic name
     associate paste .menubar.editMenu Paste
     associate paste .toolbar.paste
     associate paste .popupMenu Paste

     ....

     # enable only if there's something on the clipboard
     if {there is nothing on the clipboard} {
         disable paste
     } else {
         enable paste
     }

All that's left is to write the procs associate, enable and disable.

Associate is simple:

     proc associate {what args} {
         global widgets
         lappend widgets($what) $args
     }

enable and disable are also pretty simple:

     proc enable {what} {
         global widgets
         foreach item $widgets($what) {
             set widget [lindex $item 0]
             if {[winfo exists $widget]} {
                 if {[winfo class $widget] == "Menu"} {
                     set index [lindex $item 1]
                     $widget entryconfigure $index -state normal
                 } else {
                     $widget configure -state normal
                 }
             }
         }
     }



I've used a variation of this for years and it works great. It's a pain 
   to have to associate widgets with a symbolic name, but it's worth the 
effort. Besides the obvious benefits, it makes the code easier to 
maintain in that if you change widget paths or add or remove widgets you 
only have to change the related "associate" commands rather than hunting 
down hard-coded widget paths throughout your code.

There are lots of things you can do to make the code even more fancy. 
For example, you can support accelerators, build your own widget 
wrappers that do the "associate" step automatically, add a disassociate 
step, etc.

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[Arts and crafts of Tcl-Tk programming]