Comment 4 for bug 1467961

Stephen. I punched "This bug affects me". You might want to do the same on mine if you determine it is the same as your bug. It appears to me that there is another reported bug that is the same, bug #1460285 dated 05/30/2015:

https://bugs.launchpad.net/ubuntu/+source/xfce4-panel/+bug/1460285

"Ubuntu" appear to be snowed under with reported bugs, and I guess this is just a minor one.