[REGRESSION] QApplication::keyboardModifiers() ignores Shift key modifier (Macintosh)

If you have code that calls QApplication::keyboardModifiers() or QApplication::queryKeyboardModifiers(), and the shift key is held down when either of these functions is called, the response will not indicate that the shift key is held down when it is in certain situations.

So far, the only situation in which I have encountered this bug is when code is called as a result of an action in a menu bar being triggered. If the same code is called as a result of the action being triggered by a tool button press, I do not see the bug.

To reproduce:
1. Build and execute the attached test case.
2. Hold the Shift key down and click the "Show Dialog" tool button. The label in the dialog will indicate that Shift was held down.
3. Close the dialog.
4. Hold the shift key down and click the "Main" menu item and click the "Show Dialog" action. The dialog will incorrectly indicate that Shift is not depressed.

Using the attached test case, I can reproduce this in 5.2.0 but not in 4.8.5. Those are the only versions I've tried. I also don't see this bug using Windows 7.