title: Filter Qt signals like one filters events
body: <p>With Qt, I can filter all the <code>QEvent</code> events my application receives or produces with:</p>
  
  <pre><code>qApp.installEventFilter(my_filter_object)
  </code></pre>
  
  <p>Is there any way to filter Qt <strong>signals</strong> (of <a href="http://doc.qt.io/qt-4.8/signalsandslots.html" rel="noreferrer">signals and slots</a>) in a similar manner I can filter <code>QEvent</code> events?</p>
  
  <p>With <a href="http://doc.qt.io/qt-4.8/qstatemachine-signalevent.html" rel="noreferrer"><code>QtCore.QStateMachine.SignalEvent</code></a> extending <code>QEvent</code>, and <code>StateMachineSignal</code> <a href="http://doc.qt.io/qt-4.8/qevent.html#Type-enum" rel="noreferrer"><code>QEvent.Type</code></a> being there, everything seems to be in place, but my event filter can't seem to catch one of these.</p>
  
  <p>IOW, is there any way to get the signal's name (index), the signal emitting object, and the passed arguments, for each signal of every <code>QObject</code> in my application without explicitly connecting to it?</p>
  
  <p>Thanks!</p>