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);
Use a proper "progress" signal instead of a property "notify" one
to update the on-canvas progress widget.
This way the graph is not invalidated while processing it
