A window frame assembly for use in a vehicle body panel. The assembly has a frame portion with an inner and an outer periphery. Two channels are provided in the inner periphery of the frame to support one or more sliding window panes and at least one fixed window pane. A channel is also provided in the outer periphery of the frame. The sliding window pane is adapted to close the central portion of the frame and is slidable to a position substantially adjacent one of the fixed window panes. A sealing member is received in the channel supporting the fixed window panes to provide a sealing interface with the sliding window pane, at least when it is closed. An elastomeric cover is supported from the channel in the outer periphery as well as that channel in the inner periphery of the frame in which the fixed window panes and the sealing member are received. The cover has a peripherally extending centering lip which cooperates with the body panel to prevent contact between the frame and the body panel during the procedure by which the window frame assembly is mounted onto the vehicle.