Sometimes, if you join a lot of channels, or PM a lot of people, the tabs on top of the chat can get a little hard to manage.
So there’s now an alternative option – tabs on the left of the chat.

You can toggle between the two by pressing [alt+up]. You can also set which you’d like to be default in your prefs, and set the width of the tabs if they are on the left of the chat (Prefs->General->Tabs).
Note that since I took the screenshot, I’ve moved the closers to the left side of the tabs, so that if the tab name is too long, you can still get to the closer.
Please note this feature is not available in IE6 due to IE6 being the worst piece of software ever written since time began. Seriously… It’s like it was written by fish.
Enjoy