My planted freshwater community has overtank lighting and is just open top.
I've never had a fish jump (because i choose my fish carefully in light of the tank being open top), I'm careful what i spray in the room (no air freshener etc) and contrary to popular belief, most homes in the UK are actually too dry due to central heating rather than too wet, so you'd have to really try to get damp from having an open-top tank. You could actually say it's a good thing. Anyway, if you're worried, all you need is a de-humidifier, but i've never bothered.
I've never had any problems with it at all, and it opens up new worlds in the planted tank game.
You can see pics in the link in my sig below.
Cheers
BTT