Abstract: The invention relates to window framing systems which use corner keys, and which seal against embossed surfaces, particularly for use in garage doors. The corner keys are insertable into hollow portions of extruded window frames and which preliminarily hold the window frame together prior to more permanent fastening within a garage door by a plurality of screws or even via a snap-fit arrangement. The angularity of at least two internal ribs of the corner key into which a fastener impinges thereupon, facilitates tightening engagement of each mitered window frame corner, leading to a superior appearance and preventing moisture from getting inside the window unit by the positioning of a sealing surface which seals on an edge of a door or panel.