Abstract: A channel which extends along a periphery of a panel member is initially provided on at least part of an inner wall thereof with a thin coating of a solid but tacky material which provides a high friction gripping surface. An edge portion of a fabric sheet, which covers a side face of the panel member, is engaged with the tacky coating and retained in the groove by a deformable retainer. The coating is preferably applied to an inner wall of the channel as a liquid, and is distributed over a greater area of the channel wall by an air nozzle which spreads out the material so that it not only extends lengthwise along the channel but also transversely over a significant width, thereby creating a significant contact area for gripping engagement with the edge portion of the fabric when the deformable retainer is inserted in the groove.