[Carbon] QListWidget repaint issue - Mac only

Attached sample project reproduces problem 100% on Mac.

Steps to reproduce:
1) Install LGPL Qt SDK for Mac: qt-sdk-mac-opensource-2009.04.dmg
2) build attached sample project
3) start app and click 'open USB link' button and after about 5s, some timestamps will appear in the list widget.
4) next click on the tree widget on right (this widget now gets focus)
5) click on 'get directory' button

expected: the list widget will be cleared and new timestamps should appear

result: no timestamps will appear unless you select the list widget

If I get rid of the tab widget and place the list and tree widget directly on the main window, then the problem does not happen.