I tried this several times, reloaded, closed out all windows, opened in a new one, etc. Both BTD5 game and room chat were showing nothing. I loaded with a different game, and voila, room chat worked fine.
The room could see what I had typed while on BTD5, but I couldn’t see anything by anyone. Not sure if this is just me, or if it’s a glitch. Just wanted to put it out there.
iMac, OSX 10.7.2, Safari 6.0.3