/// <summary>
///
/// </summary>
/// <param name="caption"></param>
/// <param name="index"></param>
/// <param name="callback"></param>
/// <returns></returns>
public GButton AddItemAt(string caption, int index, EventCallback1 callback)
{
GButton item = CreateItem(caption, callback);
_list.AddChildAt(item, index);
return(item);
}