I say the timestamp is way too long. I agree with it should be a Treebar, instead of a switch.
It's more organized that way. And in my opinion looks cleaner.
You have too many tabs in your CHAN popups a lot you can easily combine. (I.e. Admin Access/Admin Protect/IRC-D-Admin Commands.
That should help clean it up a bit more.
i hate the treebar tis why i don't use it:) but anyone that wants to can easily change out the switchbar to the treebar via the view menu. as for the combining ircd admin commands would not be smart to combine with admin access/admin commands seeing how they are completely different things. but eh.
I don't like the normal treebar, but if you right click on some empty space and un-check "use folders" it becomes a quite bit more tolerable.
I'm with xdesoto, though not on the menus he specified, that the menu list, especially for the nick list, is a little cluttered. I'm of the opinion that if it isn't directly related the the select nick(s) then it shouldn't be in the nicklist menu. Leave channel menus to the "menu channel { }" definition.
Over all looks interesting, and I'm in no way bashing you for your hard work. Just giving you some constructive criticism.