Comment 34 for bug 248324

The GNOME desktop runs with user privileges, not root. The error messages in Craig's experiment were not because there's another panel already running (I guess this is why xe said it was expected), but because there's no running GNOME session for the root, and hence the panel application can't connect to it. But this error is not fatal to the panel, so it keeps running, hiding the old panel behind it. (Proof: if you kill it in the terminal via a Ctrl+C, the old panel is back, so it's not replaced, only obscured.)

This has a very nasty side-effect: the new panel runs as root, and if you launch any programs from it, they will also be run with root privileges. (Proof: open a terminal from the Applications menu, and check your user name.) This is bad; you shouldn't use root privileges for your daily work.