I think there is a bug on how markAllMatchesForText is called by webkit_web_view_mark_text_matches. In webkitwebview.cpp line 1736 the parameter shouldHighlight is called with 'false' and should be 'true'. The function returns the amount of matches, but don't highlight the matches at all. The docstring indicates that though. So either the docstring is wrong or the function call. This bug is found in webkit vers. 1.0.1.