Note that we do not use the Link and LinkVisited roles when rendering rich text in Qt, and that we recommend that you use CSS and the QTextDocument::setDefaultStyleSheet() function to alter the appearance of links. For example:
C++ (Qt)
QTextBrowser browser;
QColor linkColor(Qt::red);
QString sheet = QString::fromLatin1("a { text-decoration: underline; color: %1 }").arg(linkColor.name());
browser.document()->setDefaultStyleSheet(sheet);