How `g_type_class_peek ()` was used it didn't return the correct parent
class in most cases.
G_DEFINE_TYPE macro creates a pointer we can use to get the parent
class `n_p_parent_class`.
Because we didn't use the correct parent class the object initialisation
wasn't fully completed for some GtkWidgets.
See https://developer.gnome.org/gobject/stable/chapter-gobject.html#gobject-instantiation
for more information.
This commit makes use of the `n_p_parent_class pointer` created for this
specific use case where ever possible.
Fixes: https://source.puri.sm/Librem5/calls/issues/118
* Make the Answer button look nice and laid out properly.
* Merge the time and status labels, displaying simply the text
"Calling..." until the call becomes active and then the call time
afterwards.
* Fix info display bar in both the call and main windows so they use a
GtkRevealer and work a lot better.
* Add a "new-call-symbolic" icon for the "Add call" button.
* General tweaks and clean-ups
Closes#55Closes#35
The return value of this callback, used for the call selector flow
box, should have a reference added to it. The callback's return value
is annotated as "transfer full".
