Tried dragging a header in. Tried deleting it by pressing "del" after selecting it, didn't work. Tried dragging it off-screen to delete it, didn't work. Then I noticed the welcome-message chatbox on the bottom right was hiding a big red button ;)

I can imagine keyboard support wasn't the highest priority in getting all of this stuff to work though, so not complaining, but I think it would make this a lot more appealing to power-users.