Nevermind, after a week of fiddeling around I finally found the problem. He forgot to release bitmaps he created during runtime. In all of the elements. Had to go through thousands lines of code.. what a waste of time!
That sucks.. Maybe you could reupload fixed version in original thread, so no one will need to fix this again?
Yeah I will, just need to get rid of some small leaks. They are only seen when using LBGUI intensively.