xmsetmnemonic, widgetID, string
[motif package] Sets a short-hand keystroke for the widget with the
widgetID. The first character of the
string is taken for the short-hand keystroke. If the
widget is a menu bar item and if the short-hand keystroke appears in the
menu bar item title, then then the short-hand character is underlined in
the menu bar item title.
See also: xmmenubar