[Страдалецъ]

Примерно так:

Код:

...

var
  Form8: TForm8;
  n: Integer;

...

function EnumWindowsProc(wHandle: HWND; Param: Pointer): BOOL; stdcall;
var
  Title, ClassName: array[0..255] of char;
begin
  GetWindowText(wHandle, Title, 255);
  GetClassName(wHandle, ClassName, 255);
  if IsWindowVisible(wHandle) and (ClassName = 'TForm8')
  then begin
       Inc(n);
       SetWindowText(wHandle, Format('Кукарямба %d', [n]));
       end;
  Result := True;
end;

procedure TForm8.Timer1Timer(Sender: TObject);
begin
  n := 0;
  EnumWindows(@EnumWindowsProc, 0);
end;

...