Greets,
my first suggestion here, and the one that annoys many of you I'm pretty sure

when connecting to server, and you have a script which joins many channels (or for example joining a channel by hand, and due to lag window opens later), the newly opened window will steal focus from the active window! so if i'm typing something in a channel, and then suddenly new channel window opens, i would end up typing in the new window, and send half of message to the new window!
thats so annoying, and so pretty easy to fix (i guess)..
thanks!