Is it possible to change the Save game window or the exit window, concerning the sprites? I know I can change the text on the main script, but what about the sprites, is it possible or not?
Want help in here! I customised all of my GUI but that seems to escape me, and it blurrs all of my work with all that gray :P
Not if you're using the internal savegame or quit interfaces (these internal interfaces actually use no sprite, except the inventory interface).
You can however, make your own GUIs, so you can use whatever sprites you like.