/////////////////////////////////////////////////////////
//Insert a line number at the beginning of each line  //
////////////////////////////////////////////////////////
var  
  doc,i;

begin
  doc := Application.ActiveDocument;
  
  doc.lockDisplay;
  try
    for i := 0 to doc.lines.count-1 do
      doc.Lines.strings[i] := IntToStr(i) + ' ' + doc.Lines.strings[i];
  
  finally
    doc.UnlockDisplay;
  end;
end;