This is required by LibreOffice Console, actually I need to activate it using xrandr –output VGA –auto –pos 0×800 That works for me very well extending my desktop to other virtual desktop.
Thank you for your bug report. This is implemented in the git master branch and can be tested in xfce4-settings-4.11.0 (development release). *** This bug has been marked as a duplicate of bug 7465 ***