http://www.purl.org/tcl/home/man/tcl8.4/TkCmd/selection.html
Can someone write up some text distinguishing the terms for 'inter-widget text highlighting for copy/paste purposes' and 'user initiated indication of widget component indication' - in other words, distingushing the concept of 'selecting text in a text widget or whatever' vs 'selecting listbox items'...
See also:
Tk syntax help - Arts and crafts of Tcl-Tk programming - Category Command