fullscreen vs alt+click/alt+drag

["P. George" <invest juun com>]

i'm porting a fullscreen, kiosk-like app from the mac to linux/x86.

everything's hunky-dory so far, except that there is a critical feature 
of the app which isn't working as it should:

i need the user to be able to alt+leftclick my app's interface (ie: the 
main, fullscreen window) to gain access to certain features, but when i 
do this on linux (in _almost_ every window manager), of course the 
window (even though it's fullscreen), is able to be moved around.  i 
realize this is standard fare for linux gui apps, but not for kiosk 
apps or games.

i tried looking through some source for a couple games, but i'm not 
seeing anything unusual that might take care of this problem, even 
though the games themselves definitely do not allow alt+dragging of the 
game window.

so, what's the trick?

thanks.

- philip