Here is a script to display each widget available in Tk. 
It made the assumption that all widgets begin with a lowercase letter.

 #
 # the dynamic list of Tk widgets
 #
 package require Tk;

 set tkCommands [lsort [info commands "::tk::\[a-z\]*"]]

 foreach cmd $tkCommands {
         puts [string range $cmd 6 end]
 }


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