A panel element includes a fabric panel, a corner gasket element and two auxiliary gaskets. The corner gasket element has a tab member and two gasket legs. Each leg extends to respective outer ends from a common intersection in a manner orthogonal to one another. The tab member extends from the intersection in a manner orthogonal to the legs. The auxiliary gaskets each have at least one gasket end positioned adjacently to a respective outer end. The fabric panel has a display face and an outer perimeter portion. The outer perimeter portion is affixed to the gasket legs and the auxiliary gaskets. The gasket legs and auxiliary gasket elements are removably insertable into a perimeter groove disposed in the closed-contour framework, thereby facilitating tensioned attachment of the fabric panel across an opening defined by the closed contour with said tab member gripably protruding outward of the display face.