ctrlutil.go
func FindChild(parent, control Control) Control {
	var res Control

	if parent == control {
		return parent
	}

	for _, ctrl := range parent.Children() {
		if ctrl == control {
			res = ctrl
			break
		}

		res = FindChild(ctrl, control)
		if res != nil {
			break
		}
	}

	return res
}
func FindChild(parent, control Control) Control {
	var res Control

	if parent == control {
		return parent
	}

	for _, ctrl := range parent.Children() {
		if ctrl == control {
			res = ctrl
			break
		}

		res = FindChild(ctrl, control)
		if res != nil {
			break
		}
	}

	return res
}
// FindChild returns control if it is a child of the parent and nil otherwise