Attached is a patch that makes a `mouse-1' click on a minor-mode lighter in
the mode line raise its menu-bar menu, if any, as a popup.

This is analogous to what `mouse-1' does when you click the major-mode
lighter. Each minor-mode lighter brings up its own menu. If a minor mode has
no menu-bar menu, then `mouse-1' displays a message stating that.

Currently, `mouse-1' does nothing here, so this is an addition.

Example: Minor mode Icicles has lighter "Icy" in the mode line, and it has a
menu-bar menu `Icicles'. Whether or not the menu-bar is showing, if you
click the lighter "Icy" then the `Icicles' menu pops up.