In a fabric enclosure such as a tent wall there is provided an opening in the fabric panel with a fabric closure panel for closing the opening having a hinge line along one side connecting the closure panel to the wall panel. The opening and the closure panel each define an edge thereof opposite to the hinge line which is curved from an end at the hinge line around to an opposite end separated from the hinge line by a non-flexible rod with the edge of the closure panel overlapping the edge of the opening for closure thereon and a flexible bowing strip attached to the edge of the closure panel which is forced into a bowed shape to apply tension to the closure panel tending to maintain the panel flat.