I actually explained it on my
browser mod page.
But here's how I think it works. The /browser command is the same window as /show_window MainHUD.Browser or Mainhud.Browser or mainhud.Browser or any variation with a capital B. This window will go to your homepage if you have one set.
If you use the command /show_window mainhud.browser without a capital B you will get a second browser window. This window doesn't have any homepage functions though.
About the tabs thing, hmm. You use fluffy.dk and eq2i.com and Allakhazam at the same time? I'll look into it, but I won't promise anything since I really haven't had time to play much. I've spent a lot more time working on UI mods recently. The reason I didn't make a tabs version is that it's a lot more work to maintain and fix two versions. I was thinking about looking at the recent problems people have been having with Profit, although I've never used it before, but I have to get my taxes done before tomorrow!