It seems that the QtWebKit tiled backing store needs the QGraphicsItem::scale function (seeQGraphicsWebViewPrivate::updateTiledBackingStoreScale). I propose to turn off TILED_BACKING_STORE if Qt version is earlier than Qt4.6 (instead of making it work on Qt 4.5 or earlier).
Created attachment 51130 [details] proposed patch
QGraphicsItem::scale is present in Qt 4.5, but it's not a Q_PROPERTY in QGraphicsObject.
i confess I do not know what is the current minimum version of Qt that QtWebKit has to support. one mentioned it is current release (4.6) and the next (4.7). If so, should we care much about 4.5? just out of curiosity.
Comment on attachment 51130 [details] proposed patch Clearing flags on attachment: 51130 Committed r56243: <http://trac.webkit.org/changeset/56243>
All reviewed patches have been landed. Closing bug.