code: def calculateSceneWidth(self):
          
          widths = []
          
          w = self.width() / 2.0
          h = self.height() / 2.0
          
          for item in self.scene().items():
              pixmap = item.basePixmap()
              thumb = pixmap.scaled(pixmap.width(), h, Qt.KeepAspectRatio)
              widths.append(thumb.width())
              item.setPixmap(thumb)
          
          return sum(widths) + self.spacing() * (self.count() - 1) + w
docs: Returns the total width for all the pixmaps for this widget.
          
          :return     <int>