RE: Modifier state?

[Drew Adams]

> Do we have a way to detect the modifier state from the Lisp 
> level, or bind commands to modifier state changes?
> 
> I'd like to run a command whenever the user presses and releases the  
> Meta (not ESC) key.  This would be on non-TTY sessions.
> 
> A lot of applications show additional info when you press Alt/Option  
> (which is Meta for me); they even update the menus with alternative  
> functions.  The user can even view a menu, press and hold Alt/Option  
> and see the menu items change.

Someone else will perhaps correct this or provide more up-to-date info, but you
might take a look at function `event-modifiers'.

See the Elisp manual, nodes Keyboard Events and Classifying Events.