howto force webkit to render all the url with underline

[numen]

i want to all the url in the browser to display with underline, but i cannot find any settings about it.
i inherit the webview paintevent function, and set the painter's font with underline, but it seems don't work.

any one can give any suggestion?
btw:

void QWebSettings::setUserStyleSheetUrl ( const QUrl & location )

Specifies the location of a user stylesheet to load with every web page.

The location can be a URL or a path on the local filesystem

it seems that this function is useful,but i don't know howto write a user style sheet,
any one can give any suggestion?
Thanks very much!