The slice get's increased by 50 items if scrolled to the bottom
and reset to the initial 75 items if scrolled back to the top.
The defined threshholds make sure that the UX still feels smooth.
Glade misleads us into thinking we need these, but the
property is somewhat confusing in GTK3. In general we don't
want `can-focus` to be true for containers, as that will
break keynav for the children. For non-containers, the
defaults are appropriate.
Instead of manually setting `can-focus`, we should just
use the default values. GTK has sane defaults.
Fixes https://gitlab.gnome.org/GNOME/calls/-/issues/366
GNOMEs HIG recommands frames around a List.
This also moves the ScrollBar to the edge of the window in the
CallHistory.
Signed-off-by: Julian Sparber <julian@sparber.net>
