Function clash 

pub fn clash(a: Rect, b: Rect, gap: f64) -> bool

Whether two rectangles come closer to one another than gap.

Exactly gap apart is clear rather than a clash: that is a valid resting position and the boundary at which layout settlement stops. This predicate deliberately does not constrain a gesture — something in the user’s hand may overlap anything; settled uses it only when transient geometry becomes a resting layout.