This is kind of an interesting and tricky option. ..If you use separate windows it might be nice and flexible for those who play the game windowed. (me) But if the ADOM view is just extended in one direction to accommodate a message area, with the play-area remaining as it is, then it's still all in one tidy window. I'm quite partial to that idea as well. (I like its tidiness.) ..Two-monitor users should be able to make good use of it as well, just by having the window positioned with the message/game split on the split between the two monitors.
Probably impossible to do this so it pleases everyone. :)