triangularly shaped cover member 3 in a frame provided for a window 1 a gasket member 3a shown in the drawing to be obliquely abutting the cover member 3 is attached to the frame of the body 4 which may be provided with a correspondingly shaped molding extruded from light metal thus the intermediate space between the window 1 and the body 4 or the molding is thus closed in this embodiment the cover member 3 and the gasket or seal 3a mounted together as a unit but manufactured as separate components provides a seal between the window 1 and the body 4 when the door 2 is in its closed condition as is shown in fig2 for instance guidance of the window 1 is unimpaired by this structure it may advantageously be a parallel guidance system see the rendition in fig2 of an open window 1 in the door 2 the door 2 is one without a frame and is fully sealed by the cover member 3 and the gasket 3a of the invention fig3 shows a rear door 2a in a closed position and fig4 depicts the door 2 39 in its opened position the cover member 3 39 and the gasket 3a 39 being.