Suppose you have 3 widondows open, for example:
- nautilus window 1, on the front
- a larger mozilla window, behind nautilus window 1
- nautilus window 2, behind the mozilla window (totally covered by it)

and want to drag a file from nautilus window 1 to window 2. You should be able
to do it like on MS Windows:

- grab the file from nautilus window on top
- take the file to the tasklist item for the other nautilus window (you can't
take it directly to the window because it's covered by mozilla)
- wait a little and the other window pops on top
- now you can see the destination window and take the file to it, but when you
drop it there, metacity thinks the mozilla window is still on top and passes the
file to mozilla.

I'm absolutely sure I'm dropping the file on the now visible destination
nautilus windows, but I get a mozilla dialog asking what to do with the file.

I suppose this is a metacity bug, because this works as expected when using sawfish.

I'm using metacity 2.8.0, as included in gnome 2.6