Wrong drag & drog behavior in QListView in Icon mode

In Qt 4.6 defaultDropAction property in QAbstractItemView was intoduced. But QListView in icon mode uses its own realisation of startDrag(Qt::DropActions supportedActions) that calls QIconModeViewBase::filterStartDrag(Qt::DropActions supportedActions) function where this property isn't used.
QDrag::exec() is called with Qt::CopyAction.