QMdiSubWindow CloseEvent isn't spontaneous

The close event of QMdiSubWindow isn't spontaneous when the user clicks on the 'X' button to close the window.

I've replicated the case by modifying your mdi example (provided as attachment).

1. Build the project
2. Open a new file
3. Close the opened file
4. Notice the output of the qDebug is always false (i.e., the close event isn't spotaneous when it should)