Right mouse button up is propagated as left mouse button up on macOS

Steps to reproduce:

1. Build the project (I've used it with kits 5.7.1, 5.6.2)
2. Run the project
3. Move mouse cursor to rectangle area (MouseArea)
4. Press left mouse button
5. Press right mouse button
6. Release left button
7. Release right button

Expected results:
Rectangle is empty (indicating that no mouse button is pressed).
This works on Windows.

Actual results:
Left half of rectangle is filled (indicating that left mouse button is pressed, even though no button is pressed).