g_variant_lookup works like g_variant_get, so using a format string of "v" only
works if the type is actually a GVariant. Since none of the hints have GVariant
values, that means every g_variant_get with a "v" format will fail.

Fix all of the g_variant_lookup calls so that they either unpack a value
directly, or use a "@" prefix when it's more convenient to fetch the value as
a GVariant pointer.

In addition, in cases where we do fetch a GVariant, make sure that we
unreference it afterward.

and drop additional checks for min/max GLib versions, it's not needed

Now that all of the elements are in place to support (dynamically) the
action icons, we can use the 'key' in place of the 'label' when the client
sends an hint requesting it.

Some other minor issues were corrected in this change, such as ensuring that
we always show *all* widgets inside of the notification window so that when
a live notification window is updated, the action box state is not then
hidden from view.

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

Prior to this commit we would always end up adding multiple pie_countdown
widgets in a number of situations when updating the notification. In modern
media player apps, many updates are sent for the lifetime of a single
notification window, leading to new drawing areas being added and counting
down with each track/information change.

Note this hasn't been noticable for quite some time, because in many of the
themes the pie countdown hasn't actually been visible due to the actions
box having become hidden completely, meaning that the actions and pie show
very briefly, and are immediately nuked on a change to the notification.

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

Each of the themes will have to detect the 'action-icons' hint passed to
them in 'set_notification_hints' to make a determination on whether or not
to use image based buttons, instead of textual buttons, in their actions
boxes.

This factory behaviour simply extends the existing checks for urgency-hint,
as well as unifying the code style between the various in-tree theme
implementations.

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

taken from:
https://git.gnome.org/browse/notification-daemon/commit/?id=b156f34