The window is a resin panel (1) with at least one pair of ribs (3) protruding on the inner surface with the ribs of each pair facing each other. Each rib has an outwardly directed tip (5). The resin panel is connected to an associated reinforcement element (2) by inserting the tips of one pair into an engagement opening (6) of the reinforcement element. Polymethyl methacrylate resin, polycarbonate resin used as lightweight material.
