Segfault in QDialogButtonBoxPrivate::_q_handleButtonClicked

In void QDialogButtonBoxPrivate::_q_handleButtonClicked(), a pointer to the clicked button is determined via the sender() method and the QDialogButtonBox::clicked() signal is then emitted. Afterwards, that pointer is reused in a switch construct.

Thus when calling QDialogButtonBox::setStandardButtons() from within a slot that is connected to the above QDialogButtonBox::clicked() signal, the pointer becomes dangling as the buttons are deleted and we have an access to a dangling pointer, possibly resulting in segfault.