Member Rara Avis
It's not really a window, so I doubt Alt-F4 will work correctly. Most likely, you'll just accidentally close your forum browser window. It's really created with DHTML, something like the dropdown menus I tried at http://piptalk.com a ways back. The few times I've seen the banner, I didn't have any trouble running my mouse pointer over it -- unless I let the pointer "linger" on it for a second or two.
If you're only going to "click on any other main forum," you might find the Nav Window icon more convenient. I changed it a few days ago to show ALL available forums, and the NW icon can be found at both the top and the bottom of most pages.