pub trait DirectControlBindingExt: 'static {
fn is_absolute(&self) -> bool;
fn control_source(&self) -> Option<ControlSource>;
fn set_control_source<P: IsA<ControlSource>>(
&self,
control_source: Option<&P>
);
fn connect_control_source_notify<F: Fn(&Self) + Send + Sync + 'static>(
&self,
f: F
) -> SignalHandlerId;
}