I use version 4.6.0 (Xfce 4.6) and when I try to shutdown the computer with the button in the right corner an error pops up which says "An error occured in the panel", then the panel restarts. When I try to shutdown via applications nothing happens. The only way is to press the power button on the netbook(Asus Aspire one). Then the system shuts down.
If the error message says there's an error with the panel, why not file the bug with the panel?
Will most likely be fixed in devel panel, since the code is handled differently.
Devel branch has been merged in master. A 4.7.0 release will follow soon. If you think this bug is not fixed? Feel free to reopen the bug.