I'm a bit baffled... I searched and can't find the thread... It's either a CSSU/thumb option (or HildonDesktop), or I set it by typing about:config in the MicroB address bar. I can't find it now, though. Sorry... Edit: Well, I rechecked my MicroB, and it doesn't open new tabs in the background anymore. But I SWEAR I had that going recently (I reflashed about a week ago...)