A workaround for making a default monitor in multi monitor environment is not working

[Somewhere over the..]

In Ubuntu 16.04(and 16.10), to specify a default monitor in multi monitor environment is possible by this command.

$ sudo cp ~/.config/monitors.xml /var/lib/lightdm/.config/

I don't know it's a right way or not, but it works. But in Ubuntu Budgie, that does not work.

I'm using Ubuntu Budgie 17.04 beta(up to dated) with Nvidia 1050ti graphic card, using Nvidia 378 drivers.
And I have 3 monitors connected to the graphic card.
I attached a monitors.xml, which works well in Ubuntu 16.04.

I think Budgie did not check /var/lib/lightdm/.config/monitors.xml or ignore it. The log on screen is always shown on another moniotor(not on the default monitor I set). I changed the owner/permission of the file(/var/lib/lightdm/.config/monitors.xml) in several ways but nothing works.

[Petr Stochl (jointer)]

I can confirm this.
I have fresh install of Ubuntu 17.04 and nVidia card with 2 monitors, one rotated. I can configure it correctly in gnome-flashback and generate correct xorg.conf in nvidia-settings, but the rotated secondary monitor is selected as primary on login screen and is not rotated.
I "fixed" the annoyance by autologin...

There is also a tip to use /etc/lightdm/lightdm-gtk-greeter.conf and put in
[greeter]
active-monitor=0 (probably 1 in my case)
but there is not such file and i am not sure where to put it.
There seems are some workarounds using xrandr and startup scripts.

It would be nice if this could work again.

[fossfreedom (fossfreedom)]

not sure gnome-control-center is the correct package here - either lightdm or lightdm-gtk-greeter is probably the correct packages to report against.