'When we update the "Zoom" slider.'

def zoom_changed(self):

    for item in self.grid_items:
        item.set_max_size(self._calculate_zoom(self.zoom))
    width = (self.view.width() - self.view.verticalScrollBar().width())
    self.grid.reflow(width)
    self.grid.setPreferredWidth(width)
