QTextCharFormat: Setting a stretch on a font used in a QTextCharFormat has no effect

Example:

#include <QtGui>

int main(int argc, char **argv)
{
QApplication a(argc, argv);
QTextEdit te;
QTextCharFormat tcf;
QFont font("times", 12);
font.setStretch(4000);
tcf.setFont(font);
te.setCurrentCharFormat(tcf);
te.insertPlainText("This is a test");
te.show();
return a.exec();
}