VBox content disappears when scrolling in a TitleWindow with Flash Player 10.1 and Safari on Mac

Steps to reproduce:
1. Create a Flex project with the attached files ( FlexTitleWindowBug.mxml and EditorDialog2.mxml)
The project was created with FB 4 and Flash Player 10.1 installed
2. Run the app targeting Safari.
3. Click on the Open button
4. The title window opens with the three VBoxes (filled with different colors).
5. Scroll down and up several times ( ~ 6 or 7). In our actual app, the bug appears the first time you scroll down, in this example it takes a little bit more scrolling.

Actual Results:

• After scrolling down and up several times, some of the VBox content disappears. It is replaced by white sections. In this specific example, you can see how the close button disappears. In our actual app, many controls disappear.

Expected Results:

• The content in each VBox is displayed and it is not altered by scrolling

Workaround (if any):

• None

This only happens on Safari ( 4.X or 5) and Mac. Firefox on Mac doesn't have this issue.