I think PNP is actually asking about the glass into the quarter window frame, not the quarter window frame into the door main frame.
The glass is bedded in a thin composition gasket, the type I use you rub with a little engine oil and it then swells after you've fitted it and holds the glass tight. You trim later with a razor blade. Try an autoglass shop, here is a screen shot of the material.
Yours
Vern