Hi, thanks for the answer!
I haven't found the link for the internal search before, now I'm aware of it. =P
Anyway, when I tried the strategy you suggested, the graphics in the new window "crash" suddenly, a little after it has been created. However, my game is already somewhat complex, so I think this problem could be related to references to the older window (because all images have to be given a reference to the window when loaded)...
I'll try to clean up all references to see if it solves the problem.
Thanks again!