Qt Modal/Modeless possible bug in MS Windows

In Qt 4.4.0, Windows platform:
1. I create a modeless QDialog.
2. "show ()" it.
3. Open a Modal window (example, a "QFileDialog::getOpenFileName").
4. When it returns, the modeless windows is inaccesible (freeze).

In Linux, there is no problem.

What happens?

Thanks in advance.

Edit: QWidget tried and the same problem.

Solved: The QMainDialog never can be Modal. Put "setWindowModality (Qt::NonModal );" in its constructor.