Recovered Fullscreen function in QML for osx a border at top

In 5.2 QtQuick at a bug that would not allow a fullscreen button on the titlebar. It has been restored in 5.2.1 however, 'fullscreen' window retains a grey bar across the top exactly where the system menu would be. The system menu is hidden in fullscreen mode so grey bar is visible.

Not also that the same WindowFullscreenButtonHint flag used in a C++ created window in 5.2 did not have the problem.