def on_execute__set_surface_alphas(self, request):
        '''
        .. versionchanged:: 0.12
            Queue redraw after setting surface alphas.
        '''
        data = decode_content_data(request)
        logger.debug('[on_execute__set_surface_alphas] %s',
                     data['surface_alphas'])
        for name, alpha in data['surface_alphas'].iteritems():
            self.parent.canvas_slave.set_surface_alpha(name, alpha)
        self.parent.canvas_slave.render()
        gobject.idle_add(self.parent.canvas_slave.draw)