A vehicular window assembly includes a frame, a fixed window panel bonded to a lower frame portion and a movable window assembly. The side frame members of the movable window include upper and lower guide elements that are slidably received in respective channels along opposite portions of the frame. The channels are configured to move the movable window along the fixed window panel when the movable window assembly is at least partially opened and to move the movable window to a position where the movable window panel is generally coplanar with the fixed window panel when the movable window assembly is closed. When the movable window is in its closed position, a seal sealingly engages an inboard surface of the side frame members and an inboard surface of the upper frame member and an inboard portion of an upper perimeter region of the fixed window panel.