gtkapplication-dbus: Initialise screensaver-active property

See merge request Librem5/gtk!9

When GtkApplication starts listening to the screensaver's D-Bus
status, the screensaver-active property is not initialised and
applications making use of the property are out of sync until the
first state change.  Any application starting when the screensaver is
active will think it's inactive.

To fix this, we set the property when we first start monitoring the
screensaver.

This helps GtkfontChooserDialog fitting in mobile phone screens.

Drop the minimum number of characters for the filename entry, and
instead expand it. This helps it fit in narrow screens.

This avoids overloading the headebar, and lets the save entry be
populated just below it, where there is room.

Fixes Librem5/Apps_Issues#99.

This will help the infobars fit on phone screens.

That is when initially maximized windows are expected to be maximized,
not just before realizing them.

This is less agressive than resizing all resizable windows.

This will allow to drop the close buttons and make the transient windows
look like proper mobile dialogs.

This will make them look better on phone screens.

This will allow to drop the close buttons and make the dialogs look like
proper mobile dialogs.

This will make them look better on phone screens.

This makes it nicer on phones by avoiding having to scroll too much on a
touch screen and it makes it match the changes we applied to WebKitGTK
for the same reasons.

This makes the dialog work better with horizontally constrained screens.

This will be used to reveal/conceal the file chooser sidebar.

This is imported from HdyViewSwitcherBar from libhandy 0.0.10.

This is imported from HdyViewSwitcher from libhandy 0.0.10.

This is imported from HdyViewSwitcherButton from libhandy 0.0.10.

This is needed to port libhandy classes.

This will help importing Handy classes.

cellrendererpixbuf: Use fallback icons with icon-name

See merge request GNOME/gtk!729

This gives us a better chance of finding an icon to show.

Closes: #1809
(cherry picked from commit fbe0e328137714de00cd1b7d47f77b539092ac9a)

gtkplacessidebar: Add loop devices

See merge request GNOME/gtk!722

Print dialog, CUPS: Check unknown option values whether they are actually custom settings - Backport to GTK 3.24

See merge request GNOME/gtk!717

Set always correct custom page size.

build: remove unused checks for sockaddr_un.sun_len

See merge request GNOME/gtk!708

It sets HAVE_SOCKADDR_UN_SUN_LEN which is unused since d3ab2fe1