Abstract: A closure assembly of an opening in a building has at least two mutually pivoted panels mounted with the pivot axis at least substantially vertical. The panels are movable between a closed condition whereby the panels provide at least a partial closure of the opening in or substantially parallel to the plane of the opening, and an opened condition whereby the panels, mutually disaligned by having pivoted towards each other, are substantially clear of the plane. A proximate panel is pivoted by a vertical pivot axis substantially in the plane of the opening adjacent a vertical periphery of the opening. The distal region of the distal panel is supported by a supporting runner. The supporting runner is guided by a support track which is skewed with respect to the plane of the opening and which spaces the supporting runner out of the plane of the opening at the vertical periphery.