Function row

fn row(
    ui: &mut Ui,
    id: Id,
    payload: DragPayload,
    selected: bool,
    button: Option<&str>,
    contents: impl FnOnce(&mut Ui),
) -> (Response, bool)

One list row: a drag source with a click-sensing overlay (select / double-click / context menu) and an optional action button on the right. Returns (row response, button clicked).