A Qt-specific specialization of the generic PDOMVisitor.  This class provides
 * an empty implementation of {@link #leave(IPDOMNode)}, but required implementations to
 * provide {@link #visit(IPDOMNode)}.  The class also provides a few commonly required
 * implementations.
A Qt-specific specialization of the generic PDOMVisitor.  This class provides
 * an empty implementation of {@link #leave(IPDOMNode)}, but required implementations to
 * provide {@link #visit(IPDOMNode)}.  The class also provides a few commonly required
 * implementations. | QtPDOMVisitor.java