ctrlutil.go
func ActiveControl(parent Control) Control {
	fnActive := func(c Control) bool {
		return c.Active()
	}
	return FindFirstControl(parent, fnActive)
}
func ActiveControl(parent Control) Control {
	fnActive := func(c Control) bool {
		return c.Active()
	}
	return FindFirstControl(parent, fnActive)
}
// ActiveControl returns the active child of the parent or nil if no child is
// active