Function attach_composite_tooltip_boxed 

pub fn attach_composite_tooltip_boxed(
    ctx: &mut BuildContext<'_>,
    anchor_id: WidgetId,
    content: Box<dyn Widget>,
    delay: Duration,
) -> WidgetId

Variant of attach_composite_tooltip that takes an already-boxed body. Used by per-widget .composite_tooltip(...) setters that store Box<dyn Widget> so the user-supplied content can survive across the borrow boundary into build().