title: Qt signals & inheritance question
body: <p>I am relatively new to programming with Qt and had a question.  Short version:</p>
  
  <p>How do I inherit signals defined in superclasses?</p>
  
  <p>I am trying to subclass someone else's nicely made QTWidgets to change some of the default behavior:</p>
  
  <pre>
  
  //Plot3D is a QWidget that defines a signal "rotationChanged"
  class matLinePlot : public QObject, public Plot3D {
  
      Q_OBJECT;
          //etc...
  public:
         //etc...
  
          //Catch Plot3D's signal "rotationChanged" and do some magic with it:
      void initPlot(){
                QObject::connect(this, SIGNAL(rotationChanged( double , double , double )),
              this, SLOT(myRotationChanged(double, double, double)));
      }
  };
  </pre>
  
  <p>The problem is in the QObject::connect line.  What I would like to do is connect the rotationChanged SIGNAL (from qwt3D_plot.h) to a local function/SLOT - "myRotationChanged".  However whenever I do this, at run time I get:</p>
  
  <blockquote>
    <p>Object::connect: No such signal matLinePlot::rotationChanged(double, double, double) </p>
  </blockquote>
  
  <p>in C:...\matrixVisualization.h.   Of course, I know that <code>rotationChanged</code> isn't in <code>matrixVisualization.h</code> - it's in <code>qwt_plot3D.h</code>, but I thought that since I inherit from <code>Plot3D</code> everything should be fine.  But, now that I think about it, since SIGNAL and SLOT are macros, I assume <a href="http://en.wikipedia.org/wiki/Qt_%28toolkit%29#Meta_object_compiler" rel="noreferrer">MOC</a> doesn't know/care about inheritance.</p>
  
  <p>Which leads me to my question - since MOC and SIGNALS / SLOTS don't seem to know about inheritance etc: how can I subclass a widget defined somewhere else and get access to the widget's signals? </p>
  
  <p>I have a lot of examples of how to use encapsulation to accomplish something like this, but I'm afraid I don't understand how to do this with inheritance.</p>
  
  <p>Sorry if this is a ridiculous question - I feel like I'm missing something obvious.</p>