An interior rearview mirror system suitable for use in the interior cabin of a vehicle is provided that includes an interior rearview mirror assembly having an interior rearview mirror support adapted for attaching to a windshield or header portion of the vehicle. An access kerf, and a registration kerf, at different levels in the active edges, along with a registration step in one active edge, permit the panel to be inserted, or removed, by successive hinge actions. A geometry engine identifies a group of overlapping strokes from an overlay of the plurality of form images.