private void OnSourceOut() => Diagram.DeactivateElement();
private void OnTargetOut() => Diagram.DeactivateElement();
private void OnAnchorOver(NodeAnchor anchor) => Diagram.SetActiveElement(this, anchor, HoverType.Anchor);
private void OnControlPointOut() => Diagram.DeactivateElement();
private void OnControlPointOver(ControlPoint control_point) => Diagram.SetActiveElement(this, control_point, HoverType.ControlPoint);
protected void OnLinkOut(MouseEventArgs _) => Diagram.DeactivateElement();
protected void OnLinkOver(MouseEventArgs _) => Diagram.SetActiveElement(this, HoverType.Link);