More than 2000 lines of code less in app/, instead of
if (instance->member)
{
g_object_unref/g_free/g_whatever (instance->member);
instance->member = NULL;
}
we now simply use
g_clear_object/pointer (&instance->member);
which lets the user select a buffer from all available drawables and
projections to be used in a gegl:buffer-source node. The widget's
appearance is scheduled for improvement.