void g_object_interface_install_property ( GObjectTypeInterface* g_iface, GParamSpec* pspec )
Add a property to an interface; this is only useful for interfaces
that are added to GObject-derived types. Adding a property to an
interface forces all objects classes with that interface to have a
compatible property. The compatible property could be a newly
GParamSpec, but normally
g_object_class_override_property() will be used so that the object
class only needs to provide an implementation and inherits the
property description, default value, bounds, and so forth from the
This function is meant to be called from the interface’s default
vtable initialization function (the
class_init member of
GTypeInfo.) It must not be called after after
been called for any object types implementing this interface.
pspec is a floating reference, it will be consumed.