Ezmind

function EnumWindowProc( hWnd:HWND; lParam: LPARAM ):bool; stdcall;
var
  pid: DWORD;
  buf: string;
begin
  if (not IsWindow(hwnd)) or (not IsWindowVisible(hwnd)) then // || GetParent(hwnd)!=0)
  begin
    result := true;
    exit;
  end;

  GetWindowThreadProcessId(hwnd, @pid);
  if (pid = 0) then
  begin
    result := true;
    exit;
  end;

  SetLength( buf, 256 );
  GetWindowText(hwnd, pchar(buf), 256);
  if (buf = '') then
  begin
    result := true;
    exit;
  end;

  form1.Memo1.Lines.Add(buf)
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  EnumDesktopWindows(HDESK(0),@EnumWindowProc, 0);
end;