You KNOW the feeling. You're in a public space, watching and taking part in public chat. At the same time, you are in one or more IM conversations. And each time you start typing in one of your IMs, all the view behind your active IM window is GONE! It's now the muddy brown/grey of your window background and you can't see a thing.
Ok, here is an idea. A menu option that allows you to KEEP the transparency of particular windows (e.g. Communication). How would this work? Simple: with that option selected, when you click in the window THE ONLY THING THAT BECOMES NON-TRANSPARENT IS THE INPUT LINE FOR TYPING. So you can type away quite happily, but the previous part of your conversation is still in a transparent window, and you can still see what is happening in the public space where your avatar is.