listbox.go
func (l *ListBox) RemoveItem(id int) bool {
	if id < 0 || id >= len(l.items) {
		return false
	}

	l.items = append(l.items[:id], l.items[id+1:]...)
	return true
}
func (l *ListBox) RemoveItem(id int) bool {
	if id < 0 || id >= len(l.items) {
		return false
	}

	l.items = append(l.items[:id], l.items[id+1:]...)
	return true
}
// RemoveItem deletes an item which number is id in item list
// Returns true if item is deleted