Is this happening from virtualbox? Does installing virtualbox-guest-utils virtualbox-guest-x11 and restarting fix the issue? If it does then http://git.xfce.org/xfce/xfdesktop/commit/?id=05adaa59dbedd89b3e0ae6001ff367572c1be7d2 Should fix it.
Is this happening from virtualbox? Does installing guest-utils virtualbox- guest-x11 git.xfce. org/xfce/ xfdesktop/ commit/ ?id=05adaa59dbe dd89b3e0ae6001f f367572c1be7d2
virtualbox-
and restarting fix the issue? If it does then
http://
Should fix it.