ctrlutil.go
func FindFirstActiveControl(parent Control) Control {
	for _, curr := range getLinearControlList(parent, nil) {
		if curr.Active() {
			return curr
		}
	}
	return nil
}
func FindFirstActiveControl(parent Control) Control {
	for _, curr := range getLinearControlList(parent, nil) {
		if curr.Active() {
			return curr
		}
	}
	return nil
}
// FindFirstActiveControl returns the first active control of a parent