The Inner Heavyweight Container is not shown properly.

This problem occurs with Windows 2000 (at least), not under Linux.

* Add a new Heavyweight Container : Ok
* Remove the Heavyweight Container : Ok
* Add again a Heavyweight Container : Fails

The second and next times a Hw Container is added, the 'shadow' of the Hw Container appear in the Lightweight container (gray rectangle in the Lw Container where the Hw Container is supposed to be displayed), but the yellow Hw Container is not displayed...