public void AddBefore(ScriptLine newLine, ScriptLine destination)
        {
            if (destination == null || ScriptLines.IndexOf(destination) == -1)
            {
                destination = ScriptLines.Where(a => a.GetType() == typeof(Blank)).FirstOrDefault();
            }
            var index = ScriptLines.IndexOf(destination);

            ScriptLines.Insert(index, newLine);
        }
 public void AddBeforeSelected(ScriptLine newLine)
 {
     AddBefore(newLine, SelectedLine);
 }