secondary screen only works until login

[Xen]

Dave Stevens schreef op 29-08-2017 20:57:
> Hi,
> 
> I'm using 16.04 on a Toshiba laptop. I want to use a secondary display,
> a Samsung SyncMaster 712n. I have it connected to the Toshiba's
> external VGA port. The display powered up and showed system activity
> right up until the automatic user login took place. I had the system
> configured to log me in without asking for a password. When the login
> took place the secondary display went blank. The system control panel
> shows an unknown secondary display.
> 
> In an attempt to see where the problem lies I made a new (second) user
> with a password and required a credential check at login. When I log in
> as the new user the secondary screen mirrors the main laptop screen and
> continues to work until I logout then log back in as the previous
> (admin) user, then it blanks.
> 
> I suppose if I knew more about the graphic setup this would tell me
> where to look for more info but I don't.
> 
> Anyone have a suggestion about where to look?

Yes always just look at xrandr I guess.

xrandr is a tool you can use to make those changes.

Of course rather tiring to have to use it by hand.

xrandr -q will list all connected (and unconnected) displays in your 
system.

xrandr --output DVI-I-1 --primary --output HDMI-I-1 --clone

for example should, if DVI-I-1 exists, make that the primary display, 
and I think this would copy that screen to the HDMI-I-1 if it exists.

So the syntax is basically first --output NAME and then --something to 
affect it.

You can also set resolution with --display 1440x900 or something and 
--scale 1.4x1.0 or something, or --scale-from 1440x900 or something.

--auto will do auto configuration.

If you figure out how to do it you can create a desktop shortcut to do 
it etc.

Good luck.

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