* Packaging: Fix Debian build

* Revert "CI: Don't build for LMDE3"

This reverts commit 04592162.

allowed when using custom getter.)

This fixes a bug, where we fell back to the defined background color, if
reading an image file failed.
If that file was a user background, we didn't fall back to the defined
system background before using the color, now we do.
Only if that one is not readable either, we fall back to the color.

When calculating the rectangle height, using `get_monitor_geometry`
returns "application pixels", rather than "device pixels". We need to
multiply by the scale factor to convert to the correct value.

https://valadoc.org/gdk-3.0/Gdk.Screen.get_monitor_geometry.html

This adds the option "only-on-monitor".
Default is "auto", which means "Follow the mouse", like it was without
this option.
This goes together with linuxmint/lightdm-settings#17

Fix typo

Some changes were introduced which require GTK 3.22.

On non Debian/Ubuntu systems, the /etc/default/keyboard path does not exist.
To prevent expensive Python startup (and hundreds/thousands of stats +
follow-up loads) we'll reduce to an initial early stat, i.e. if the
non-standard file exists only then will we exectute the helper stub.

This is most useful on systems that employ systemd for the X11 keyboard
configuration (`00-keyboard.conf` from systemd-localed) so that the X server
already has the correct layout upon starting up. This approach also avoids
unnecessary xkbcomp calls forcing recompilation of non-cached assets.

Signed-off-by: Ikey Doherty <ikey@solus-project.com>

on exit, so the user session components won't fail to connect.

Based on fix for lightdm-gtk-greeter see:

https://bugs.launchpad.net/lightdm-gtk-greeter/+bug/1670933

* main-window: Calculate the really needed screen size properly

* slick-greeter: Smooth transition to the greeter screen

This option required a settings daemon and is no longer used.

Also, add new options to README and man page.