The old QWidget::event() return value question?

Question

Long years past a user asked this question on the Qt centre forum and it was left unanswered. It is still relevant, in particular in relation to QWheelEvent. In my experience, the QWheelEvent must be either accept()ed or ignore()d by an event handler, but mouse events can return true and it counts as an accept()? What have you learned in relation to the QEvent::event() return value? Obviously, a returned true does not always count as accept() and the documentation is vague, at best.