I don't know exactly how (well, now I remember: I was looking for a transparent background patch for xclock), but a while ago, in Göttingen I stumbled on a 3D file system browser, called XCruiser (you can get it with 'sudo apt-get install xcruise'). It has not been maintaned for a long while, and it can't even open the files you "travel", so it is pretty useless, albeit amazing. XCruiserIt made