Font set on QTableWidget may not propagate to horizontal header view

Consider the following example:

#include <QtGui>

int main(int argc, char *argv[]) {
QApplication app(argc, argv);

QDialog *dlg = new QDialog();
dlg->setGeometry(20, 20, 320, 220);

QTableWidget *tw = new QTableWidget(5, 2, dlg);
tw->setGeometry(10, 10, 300, 200);

QFont font("Courier", 20);
tw->setFont(font);

dlg->show();

return app.exec();
}

The expected result is that the courier font is set on the entire QTableWidget, including both header views.

The actual result is that the font is set only on the vertical header view. The horizontal header view's font is not affected.