This may be related to Bug 8529 or Bug 9501. With latest devel release of xfce4-settings, 4.11.3, on several occasion I ended up with both the laptop display *and* the external display being disabled. Having no output enabled is no fun, and I never really know how to enable at least a display. Of course switching to a virtual terminal (ctrl+alt+f1) works, but it's still a situation that should never occur for end users. So I guess xfce4-settings should always check that at least one display output is enabled, and if not, attempt to enable the main computer display.
This behavior may be aggravated by the fact that now there is no "Confirm new config" dialog when using the simplified dialog with only 4 choices (see screenshot). Switching from one to the other is definitive (the user no longer needs to confirm that change is OK), and sometimes the external monitor simply doesn't light up...
Created attachment 5880 simple 4-choice display dialog
This happens to me all the time if I'm not careful. I switch off my laptop panel when I have an external monitor plugged in. If I (1) pull out the DP cable without first enabling the laptop panel, or (2) switch off the external monitor (causing it to disconnect), I'm stuck with no active display. (Case (2) is made worse because the multi-monitor config is not restored when the monitor is switched back on.) If I make sure the box "Configure new displays when connected" is selected in xfce4-display-settings, then I now know I can hit the left arrow key a few times and then Enter to choose the first of the four display options (enabling the built-in display panel) -- but that's hardly a good solution for the general public.
(In reply to Luke Hutchison from comment #3) > If I make sure the box "Configure new displays when connected" is selected > in xfce4-display-settings, then I now know I can hit the left arrow key a > few times and then Enter to choose the first of the four display options > (enabling the built-in display panel) -- but that's hardly a good solution > for the general public. Knowing the default shortcuts can help things here: Bug 7036. I've also added a default shortcut for `xfce4-display-settings` to `Super+D` which then requires only `Alt + U` to enable the first display...
I'm having the same problem with xfce4-settings 4.12.1: there are several occasions that I might end up accidentally having no monitor enabled, with the laptop screen being completely blank and me hitting keypresses trying to activate the laptop monitor. Reproduction steps: 1. Connect external monitor to laptop 2. Bring up `xfce4-display-settings --minimal` 3. Choose the last option (to have only the external monitor active) 4. Disconnect external monitor - or suspend laptop and resume it without the monitor connected 5. Notice that the only monitor you have now is blank!
We used to only support LVDS displays in the past, but meanwhile added eDP (embedded display port) support, so your problem should be gone with Xfce 4.14. https://git.xfce.org/xfce/xfce4-settings/commit/?id=00a2c585af059f48ff5293c07c52100ae53712c6