I have reimplemented the close() call for additional functionality in my app. Now when the [X] button is pressed, it does not perform those calls, and the subprocesses generated while the app was in action does not get killed. The default QPushButton at the bottom of the dialog does the job well though.
Do you mean by that, that the close() slot is not being called?
Can you post your reimplementation?
Is this a QWidget subclass or a higher leverl, QDialog or QMainWindow?