I am sure that someone has done it, but be adventuresome and find something that works, and share it with the rest of us.

Seriously though, I have a 4 player flip top control panel and I too was concerned not only about how to mount the monitor (bezel) glass, but how thick I would be able to go without getting in the way of the flip top. I am looking at 1/4" Graylite #14 (or similar) glass so that it is tinted, so thickness was a concern, but my monitor shelf sits "in" from the sides of the cabinet about 1/2" so once I put a 1/4" piece of glass, I can use just about anything less than 1/4" to hold it. You see, for me the hinged, flip-top control panel hits the T-molding on the edges of the cabinet sides at some point (enough to open the control panel to get inside and to get to my Dreamcast to swap discs). Plenty of movement with the ability to easily open it up about 45+ degrees. I was going to get a piece of aluminium shaped like a 'L' that is the width of my monitor shelf. Carefully drill some screw holes into it, paint it black with paint made for metal, and screw it in to place leaving 1/4" for the glass (actually, I will have someone hold the glass in place while I attach the L shaped aluminium to the bottom of the monitor shelf.
I am sure that there are better ways to do this, but so far this is what I have come up with. I won't be doing mine until I order my glass (custom order for me) this week, and then it gets here.
Throw out your thoughts, maybe they will spark some great, new ideas.