point size of QFont is not correctly set in QFontDialog

I think there is a bug in QFontDialog.

A few of point sizes are defined by default in QFontDialog but if I set a point size which is not in the list it is not activated and displayed in QFontDialog.

QFontDialog *font_dialog;
QFont font;

font_dialog = new QFontDialog();

font.setFamily("Arial");
font.setPointSize(15); // or font.setPointSize(74); 

font_dialog->setCurrentFont(font);

In this sample code the next font size in the list is set but not set to "74" in the QLineEdit object. Instead it is set to 72 which is wrong. If font size "15" is set it is the same.