procedure TForm1.Timer1Timer(Sender: TObject);
Var p : TPoint;
    h : THandle;
    buf : Array[0..255] of Char;
begin
  GetCursorPos(p);
  h := WindowFromPoint(p);
  SendMessage(h, WM_GETTEXT, 255, Integer(@Buf));
  Label1.Caption := Buf;
end;