FastColoredTextBoxNS.ClearSelectedCommand.ClearSelected C# (CSharp) Method

        internal static void ClearSelected(TextSource ts)
        {
            var tb = ts.CurrentTB;

            Place start = tb.Selection.Start;
            Place end = tb.Selection.End;
            int fromLine = Math.Min(end.iLine, start.iLine);
            int toLine = Math.Max(end.iLine, start.iLine);
            int fromChar = tb.Selection.FromX;
            int toChar = tb.Selection.ToX;
            if (fromLine < 0) return;
            //
            if (fromLine == toLine)
                ts[fromLine].RemoveRange(fromChar, toChar - fromChar);
            else
            {
                ts[fromLine].RemoveRange(fromChar, ts[fromLine].Count - fromChar);
                ts[toLine].RemoveRange(0, toChar);
                ts.RemoveLine(fromLine + 1, toLine - fromLine - 1);
                InsertCharCommand.MergeLines(fromLine, ts);
            }
            //
            tb.Selection.Start = new Place(fromChar, fromLine);
            //
            ts.NeedRecalc(new TextSource.TextChangedEventArgs(fromLine, toLine));
        }

 /// <summary>
 /// Undo operation
 /// </summary>
 public override void Undo()
 {
     tb.Selection.Start = sel.Start;
     tb.Selection.End   = lastSel.Start;
     tb.OnTextChanging();
     ClearSelectedCommand.ClearSelected(tb);
     base.Undo();
 }