Can t5 be on glass?

I just bought a new t5 fixture (4x24 watt) that I was wondering if I would be able to place on the glass directly. It sits about half to one inch or so off the top of the glass. I do not like using the feet that it came with because it seems like it sits up too high. The fixture has no cooling fans so I dont have to worry about blocking those. I just wanna make sure that I do not over heat my brand spanking new $250 fixture. The manual gives no warnings about this situation.
Thanks Guys!

 

Probably OK but the bulbs might produce enough heat to crack the glass if it gets splashed. Ideally you do not use the glass it blocks something like 30% of your usable light.