Create an application that displays a QPushButton, and make sure that you set a custom stylesheet, for example the stylesheet as used in the attachment:

QPushButton *pushButton = new QPushButton(this);
pushButton->setStyleSheet("color: red;");

Furthermore, make sure that QGtkStyle is used as the application's default style. Then run the application and give the push button input focus, and you'll see that the input focus rectangle is drawn in a non-default way.