QFontComboBox/Windows: First-time population of families causes visible flicker [was: Aestethic issue in Designer's font family combo box ]

Check the attached example (drop down the font combo).
Changing its adjustSizePolicy does not seem to have an influence.

In Designer: Steps how to reproduce:

1. Open designer
2. Choose Settings -> Preferences in the menu
3. Choose the "embedded design" tab
4. Click the plus icon to add a device profile
5. Expand the "Family" combo box

Result:
Combo box flickers when it is opening and it is wider than the closed combo box

Expected result:
Combo box expands without flickering and has the same width as the closed widget

Platform: Windows 7