pub trait CellRendererAccelImplExt: ObjectSubclass {
    fn parent_accel_edited(
        &self, 
        renderer: &Self::Type, 
        path: &str, 
        accel_key: u32, 
        accel_mods: ModifierType, 
        hardware_keycode: u32
    );
    fn parent_accel_cleared(&self, renderer: &Self::Type, path: &str);
}