@dbarron Best alternative until a lightbox can be developed is using imgur. Then you can embed the thumbnail as a link to the full image.
My plasma desktop for instance, code:
[ ![](https://i.imgur.com/r9aRrU5l.jpg) ](https://i.imgur.com/r9aRrU5.jpg)
Notice the L (lowercase though) at the end of the first URL, that indicates I want a large thumbnail. Second URL is the full image on imgur.