The argument @var{menu} says what to display in the menu. It can be a
keymap or a list of keymaps (@pxref{Menu Keymaps}). In this case, the
return value is the list of events corresponding to the user's choice.
-(This list has more than one element if the choice occurred in a
-submenu.) Note that @code{x-popup-menu} does not actually execute the
-command bound to that sequence of events.
+This list has more than one element if the choice occurred in a
+submenu. (Note that @code{x-popup-menu} does not actually execute the
+command bound to that sequence of events.) On toolkits that support
+menu titles, the title is taken from the prompt string of @var{menu}
+if @var{menu} is a keymap, or from the prompt string of the first
+keymap in @var{menu} if it is a list of keymaps (@pxref{Defining
+Menus}).
Alternatively, @var{menu} can have the following form: