From the friendly QObject::eventFilter() docs:
Filters events if this object has been installed as an event filter for the watched object.
So, where have you installed this QObject as an event filter (QObject::installEventFilter())? You use this if you want to see all the events destined for another QObject before that object sees them.

If you want to see the key press events that make it to this QWidget then you want to reimplement QWidget::keyPressEvent().
If you want to see all events then reimplement QWidget::event().