Resolved potential race condition when moving slider along while rendering.

src/Workflow/ClipWorkflow.cpp

@@ -117,9 +117,9 @@ void    ClipWorkflow::unlock( ClipWorkflow* cw )
         //Signal that render has been completed.
         cw->m_renderWaitCond->wake();
 
-//        qDebug() << "Entering condwait";
+        qDebug() << "Entering condwait";
         cw->m_waitCond->wait( cw->m_condMutex );
-//        qDebug() << "Leaved condwait";
+        qDebug() << "Leaved condwait";
         cw->m_stateLock->lockForWrite();
         cw->m_state = Rendering;
 //        {

src/Workflow/TrackWorkflow.cpp

@@ -191,31 +191,42 @@ void                TrackWorkflow::stopClipWorkflow( ClipWorkflow* cw )
          cw->getState() == ClipWorkflow::Ready ||
          cw->getState() == ClipWorkflow::EndReached )
     {
+        qDebug() << "Stopping a sleeping / ready / endreached clip. Status == " << cw->getState();
         cw->getStateLock()->unlock();
         cw->queryStateChange( ClipWorkflow::Stopping );
         cw->wake();
         cw->stop();
+        qDebug() << "Stopping sleeping/ready/endreached clip";
     }
     else if ( cw->getState() == ClipWorkflow::Rendering )
     {
+        qDebug() << "Stopping a rendering clipworkflow";
         cw->getStateLock()->unlock();
         cw->waitForCompleteRender();
-        cw->queryStateChange( ClipWorkflow::Stopping );
+        {
+            QMutexLocker    lock( cw->getSleepMutex() );
+            cw->queryStateChange( ClipWorkflow::Stopping );
+        }
         cw->wake();
         cw->stop();
+        qDebug() << "Stopped rendering clipworkflow";
     }
     else if ( cw->getState() == ClipWorkflow::Initializing )
     {
+        qDebug() << "Stopping an Initializing clipworkflow";
         cw->getStateLock()->unlock();
         cw->waitForCompleteInit();
         cw->stop();
+        qDebug() << "Stopped Initializing clipworkflow";
     }
     else if ( cw->getState() == ClipWorkflow::Paused )
     {
+        qDebug() << "Stopping a paused clipworkflow";
         cw->getStateLock()->unlock();
         cw->queryStateChange( ClipWorkflow::Stopping );
         cw->unpause();
         cw->stop();
+        qDebug() << "Stopped a paused clipworkflow";
     }
     else
     {