Hi, Methy, unfortunately I found the same problem before, and is because a door or window, or any library object is one element and Graphics override does not change only a part of an element that is a library part yet, this is something I hope they add to the GO in the next versions to come.
Anyways I hope someone has found a workaround for this better than mine, that is converting to morph something that I'm pretty sure you don't want to do.