I've mailed Maarten to verify it, this commit is for test at other OSX platforms. - this was the baddie: setDrawingContextType(GHOST_kDrawingContextTypeNone); it was called in the window destructor, for each window closed. I've hacked in a temporal global var to store the mainwindow. When this line is only called for mainwindow, it all works smoothly. - next commit is needed too!