Actually, it's rather queer, at least on my iMac running 10.4.11 with X11 1.1.3 - XFree86 4.4.0.

With an xeyes (for example) window open on the root window, I click the yellow button. Nothing happens, but with cmd-opt-a I return to my desktop with the xeyes window minimized to the dock. I click on that dock icon and the root window appears, with a "warped" small xeyes window (imagine genie effect aborted) just above the bottom of the window. The pupils of the eyes are still active by the way. Creepy. Anyway, two successive cmd-opt-a's and the xeyes window is returned to normal on the root.

In summary, the Tiger behavior is also not what one would normally expect!