Hixxy: I realize that, and, after re-reading my post, I realize I could've worded it better.
KilledInAction: As a temporary solution, the * could be used, as this will cover channel and pm windows. If you want to know if it's a channel window or not, check the return from $chan.
If it's a channel window, then $chan will return the name of the channel, otherwise it'll return $null
Hixxy's notation is, realistically, if not literally, the only drawback that I know of.