a window assembly for a motor vehicle includes an opening defined by a pair of spaced apart stationary windows . above and below the opening are a pair of opposing horizontal guide rails within which a moveable window slides allowing the opening to be selectively covered or uncovered . attached to the moveable window is a vent screen , the other end of which is attached to a retraction device mounted adjacent to the opening . when the moveable window is opened , the vent screen uncoils from the retraction device , covering the opening . when the window is closed , the retraction device automatically spools and stores the screen .