QComboBox pop-up in QWebView

In Firefox/Chrome/InternetExplorer/Safari/Opera pop-ups from the combobox expand as the content (See attach).

QComboBox pop-up does not expand the content. Pop-ups are limited by the size of QComboBox (See attach).

Now this will only serve a custom QComboBox. I would like to know if you have to modify the QComboBox::showPopup used by QWebView.

More info:
http://stackoverflow.com/questions/20554940/qcombobox-and-qwebview