Function on_collapse 

pub fn on_collapse(
    child: impl IntoUiNode,
    handler: Box<dyn FnMut(&VisibilityChangedArgs) -> HandlerResult + Send>,
) -> UiNode

P Widget visibility changed to collapsed.

Preview

You can preview this event using on_pre_collapse. Otherwise the handler is only called after the widget content has a chance to stop propagation.

Async

You can use async event handlers with this property.