VGA dies after unplug except when switched to console?

[Kevin Chadwick]

On ubuntu 14.04 on a DELL optiplex 745 (internal intel gm gpu 965, I
think but I can check), if I unplug the VGA port whilst in X11 then I
find that the screen is blank/black when I plug the VGA cable back in
and I haven't found a way to bring it back aside from switching to the
console which is oddly not blank/black and rebooting.

If I remember to switch to the console before unplugging and plug it
back in and then switch back to X11 with F7? then I do not need to
reboot?

Is this a known issue or any ideas what is going on?