Short description

#2168 introduced creating selection boxes lazily. This is, however, compatibility breaking for any classes that extend ViewBox and expect the attribute to behave as it did. For example, we use these in Orange here and I am sure this is not the only place we touch it:
https://github.com/biolab/orange3/blob/269d7fa75c0f36f69b318d925c080b3626d65837/Orange/widgets/visualize/utils/plotutils.py#L156

Should we work around the issue or are you perhaps planning on reverting this? Were there any substantial gains achieved by that particular optimization? Does anyone open thousands of viewboxes quickly?