func (l *ListBox) EnsureVisible() {
	length := len(l.items)

	if length <= l.height || l.currSelection == -1 {
		return
	}

	diff := l.currSelection - l.topLine
	if diff >= 0 && diff < l.height {
		return
	}

	if diff < 0 {
		l.topLine = l.currSelection
	} else {
		top := l.currSelection - l.height + 1
		if length-top > l.height {
			l.topLine = top
		} else {
			l.topLine = length - l.height
		}
	}
}
func (l *ListBox) EnsureVisible() {
	length := len(l.items)

	if length <= l.height || l.currSelection == -1 {
		return
	}

	diff := l.currSelection - l.topLine
	if diff >= 0 && diff < l.height {
		return
	}

	if diff < 0 {
		l.topLine = l.currSelection
	} else {
		top := l.currSelection - l.height + 1
		if length-top > l.height {
			l.topLine = top
		} else {
			l.topLine = length - l.height
		}
	}
}
// EnsureVisible makes the currently selected item visible and scrolls the item list if it is required