I applied 'Enable crtc if it is disabled after power cycle' patch as provided in comment #53 by jkampe68 to the source package of xfce4-settings (4.12.0-2ubuntu1)
This fixed the issue. Thank you jkampe68.
I sincerely hope this patch or an adaptation that fixes the problem accordingly will find its way into the xfce4-repository.
On Linux Mint 18 xfce, I too got bitten by this bug.
After power off / power on, the monitor reports 'no signal'.
Intel Integrated Q45/Q43 Graphics (Dell Optiplex 780 USFF)
DisplayPort <--> DVI-D cable
Acer V243HL LCD Monitor (1920x1080 @60Hz)
I applied 'Enable crtc if it is disabled after power cycle' patch as provided in comment #53 by jkampe68 to the source package of xfce4-settings (4.12.0-2ubuntu1)
This fixed the issue. Thank you jkampe68.
I sincerely hope this patch or an adaptation that fixes the problem accordingly will find its way into the xfce4-repository.
Thanks in advance!
Luuk