listbox.go
func (l *ListBox) Clear() {
	l.items = make([]string, 0)
	l.currSelection = -1
	l.topLine = 0
}
func (l *ListBox) Clear() {
	l.items = make([]string, 0)
	l.currSelection = -1
	l.topLine = 0
}
// Clear deletes all ListBox items