Corner joint for a window or door frame

A corner joint for a window or door frame, which includes:

• first and second frame members each having a mitered end, at least one cavity in said mitered end and at least one side wall opening into said cavity,
• a screw boss in said cavity of said first frame member, and a detent lug on a flexible resilient portion of said screw boss and received in said side wall opening of said first frame member,
• an L-shaped corner key having a first leg received in said cavity of said first frame member over said screw boss and holding said screw boss in said first frame member, and a second leg received in said cavity of said second frame member,
• a sealing gasket, and
• a screw extending through said side wall opening in said second frame member and through said corner key, and threaded into said screw boss to clamp said mitered ends of said frame members together with said sealing gasket captured therebetween,
• said detent lug having an angled side face to engage said mitered end of said first frame member and cam said flexible resilient portion inwardly during insertion of said screw boss into said first frame member, registry of said detent lug with said side wall opening in said first frame member allowing said flexible resilient portion of said screw boss to snap said detent lug outwardly into said side wall opening.