(last_menu_bar_item_end): New variable.

(last_menu_bar_item_end): New variable.
(xmenu_show): Set that var.
(other_menu_bar_item_p): Return 0 if mouse is not in any menu bar item.

(xmenu_show, xdialog_show): Add casts in assignments
to widget_value fields from string contents.
(dispatch_dummy_expose): Cast arg to XtDispatchEvent.

[!USE_X_TOOLKIT] (xmenu_show): Right-justify char equivalents.
Use alloca for concatenated strings, if alloca is fast.

[USE_X_TOOLKIT] (xmenu_show): Use XtTranslateCoords.