2.51.5 Gio: * Application: get_default(): Correct the reference counting. (KJell Ahlstedt) Bug #779936 (James Legg) * Add PropertyAction. (Kjell Ahlstedt) Glib: * Remove Glib::unconst() because it is unused and unnecessary. (Kjell Ahlstedt) * Variant: Add template specialization for std::tuple, and a test. (Alexander Rössler, Kjell Ahlstedt) Bug #777791