KFileWidget::eventFilter()
(QEvent::Destroy event)
QWidget::~QWidget()
KDirOperator::~KDirOperator
KFileWidgetPrivate::~KFileWidgetPrivate
KFileWidget::~KFileWidget

In that event filter, the d pointer is in the process of being deleted,
better not use it. The event filter is only about key events anyway,
skip it for everything else.