I'm also seeing this with Linux Mint 15 and xfce4-panel 4.10.0. Workaround is to kill the panel process and restart it:
$ pkill panel $ xfce4-panel Hth Rafael -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
