Cast the g_object_ref() result
Cast the g_object_ref() result

Starting for GLib 2.54, g_object_ref() warns if we acquire a reference
on a variable of a certain type, and assign the result to a variable of
a different type.

GNOME/at-spi2-atk,GNOME/at-spi2-core,GNOME/at-spi2-core,GNOME/at-spi2-core