I think a glass lid will affect the oxygen turnover in your tank which is not a good thing. I would suggest you do the egg crate thing since it allows for oxygen to circulate. It can be purchased at your hardware store.

Maybe I wan't clear. Not glass, window screen - just the mesh part. It will still allow for air flow and a fish will certainly not be able to jump though it. Just wonding if anyone has used this instead of egg crate...

I have, and it sucked. Over time it stretches out, and is hard to keep its shape. It keeps a lot of light out, and I found that eggcrate was an improvement over mesh screen.

I've always used eggcrate but it is not perfect over the last few months I've had anthias jump through 4 times. Two lived and two died.

I just got a custom glass top cut and I have noticed no change in temp. I do have the back open where the pump etc is so heat can escape and oxygen can flow. So far so good. I don't have any complaints!