I?ve seen some strange textures with black background and white blured silouets. I imagine that they?re for the light in the windows...right? They have the same form as windows though.
The blured ones are probably textures that give off light. It should look like light coming through frost in a night map. Ones with black panes are see through windows and should have the word "frame" in the name. They should have a counter part with "broken" in the name. And, both can be used for a func_window that breaks.