Palette text colors are sometimes ignored on Mac OS

Qt on Mac OS sometimes ignores the text color set through the palette. This happens both on the native Mac OS style and on non-native styles like Plastique and Cleanlooks.

The palette text color is ignored when it is set at application startup. If the palette is changed after application startup (e.g. in response to a button press), the text color will change correctly at first. But if you click on another window, and then return to the Qt application window, the text will suddenly change back to its original default color. So the problem could be related to switching between the Active and Inactive color groups.

The attached main.cpp reproduces the problem for me on Mac OS. When I run the same code in Windows, it works correctly.