Dropping a file name on the menu bar currently opens the file in a
new
window. I think that is useful (i.e. I use it all the time :-)
It might be useful, but I'd find it confusing.
Here's a bizarre idea. If you bring up a menu and drop a file on a
menu item, the chosen command operates on that file name as argument.
Yes, that would make sense, but it seems difficult to do: when the menu
item is displayed, the mouse is typically grabbed by Emacs, and
similarly
when drag&dropping, the mouse is grabbed the other application, so
there's
a problem.