uses FileCtrl; 
 
function ExpDir(dol: TDirectoryOutline; dir: string): boolean; 
var idx, p, i: integer; 
  s: string; 
begin 
  result := false; 
  dir := trim(dir); 
  if length(dir) = 1 then dir := dir + ':'; 
  if ansilastchar(dir) <> '\' then dir := dir + '\'; 
  if (dir[2] = ':') and directoryexists(dir) then begin 
    try 
      idx := 1; 
      dol.drive := dir[idx]; 
      dol.items[idx].collapse; 
      dir := copy(dir, 4, max_path); 
      dol.items[idx].expand; 
      while dir <> '' do begin 
        p := pos('\', dir); 
        s := copy(dir, 1, p - 1); 
        dir := copy(dir, p + 1, max_path); 
        for i := idx to dol.itemcount do 
          if dol.items[i].text = s then begin 
            idx := i; 
            dol.items[i].expand; 
            break; 
          end; 
      end; 
      dol.row := idx - 1; 
    except 
      exit; 
    end; 
    result := true; 
  end; 
end; 

 
// Beispielaufruf 
procedure TForm1.Button4Click(Sender: TObject); 
begin 
  if not ExpDir(DirectoryOutline1, 'c:\programme\icq\2000b') 
    then showmessage('Fehler'); 
end;