Some of the preferences manipulated by the Qt port are missing manipulation functions in the WKPreferences C API.
We've come to the conclusion that the settings in question should not be exposed as part of the QML / Qt API and hence the API probably won't be needed.
I'll close the bug as soon as we've come to a final conlcusion.
=== Bulk closing of Qt bugs ===
If you believe that this bug report is still relevant for a non-Qt port of webkit.org, please re-open it and remove [Qt] from the summary.
If you believe that this is still an important QtWebKit bug, please fill a new report at https://bugreports.qt-project.org and add a link to this issue. See http://qt-project.org/wiki/ReportingBugsInQt for additional guidelines.