I'm stuck with the following problem :

I have a scene with several QGraphicsItems-derived instances. I make a first selection, then I want to extend it using CTRL-key and rubber band. The problem is that QGraphicsView does not seem to support extended selection due to following code :

in qgraphicsview.cpp :

Qt Code: 
  1. void QGraphicsView::mousePressEvent(QMouseEvent *event)
  2. {
  3.  
  4. // ...
  5.  
  6. #ifndef QT_NO_RUBBERBAND
  7.     if (d->dragMode == QGraphicsView::RubberBandDrag && !d->rubberBanding) {
  8.         if (d->sceneInteractionAllowed) {
  9.             // Rubberbanding is only allowed in interactive mode.
  10.             event->accept();
  11.             d->rubberBanding = true;
  12.             d->rubberBandRect = QRect();
  13.             if (d->scene) {
  14.                 // Initiating a rubber band always clears the selection.
  15.                 d->scene->clearSelection();
  16.             }
  17.         }
  18.     } else
  19. #endif
  20.  
  21. // ...
  22. }
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As you see, "Initiating a rubber band always clears the selection". So I tried to overload my scene's clearSelection() method to have my word on it, but unfortunately it's not a virtual method and thus it's not called.

I'd prefer a check at scene's level, not at item's level (indeed, i could check for QApplication::keyboardModifiers() in the itemChange() method of each item, but it's kinda intrusive)

Anybody faced the same problem ?

Thanks in advance for your answers