Matt the Exo Terra enclosures have a screen top as well as ventilation in the front door.
Looks like this
Exo Terra Glass Terrariums at UKPetSupplies.com

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Merlin,
What's Life Without A Little Magic!

ya thats the one I mean. its pritty cheap I think for something that nice. its deffinatly more visually pleasing than a regular aquarium I think and would prefer to use something like that. plus theres more hight

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Jimmy
Some of us fall and some of fly but at the end of the book all of us die

Oh yeah, I've seen those. That would be great for a tree frog. As you pointed out, it's got the vertical design they prefer.

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+5 bonus points to whoever finds me a job!

"Eagles may soar, but weasels don't get sucked into jet engines." - John Benfield

If you go with this I would suggest getting the 24X18X24 one. especially if you intend to by more than one frog. This would be ok for 1 or 2...

I wouldn't go shorter than 24" tho... If the frog isn't happy with how high they can climb they can hurt their snout trying to get past the screen to go higher.