sometimes my dropdown menus in gnome stick and cannot be removed easily. Nvidia driver problem?

[Peter Teuben]

I've installed 10.10 about a week ago, coming from Fedora, i've been 
very impressed so far. Easy to administer, sometimes names of packages 
are a bit confusing if you come from another distro such as Fedora...

I run gnome, and it seems as if a lot of GTK+ based programs where I use 
a pulldown menu from time to time have a pulldown menu that becomes 
"stuck" on the screen, and accross all desktops, i.e. as if they're 
sticky.  I can't find a reliable way to reproduce this, but so far it 
seems killing the parent will remove it (but you can't always do this) 
or else carefully trying to re-do the pulldown in the exact way, as the 
sticky part seems to remember it's original and will properly see the 
original screen again after some fiddling.

I'm very puzzled by this, have never seen this is any version of 
Gnome/GTK+ tools.

Anybody seen this before and/or know a solution to this?  I should add 
the first few days I ran with the original X driver, and a few days 
later I installed the native Nvidia,and I'm not sure if the problem was 
there before I installed Nvidia. But the fact that this is a pulldown 
that becomes persistent in X, seems to point to me to an Nvidia problem.

peter