The figure and gallery elements have support for Highslide. Why not another-thumbnail-expander?
I chose Highslide because it was the best of breed of this genre of scripts at the time when I made the choice. If another script with significant advantages over Highslide becomes available, I may add support for it too. But I am not going to code in glue for every thumbnail expander on the market. There are already too many such scripts to even keep track of. In figures & galleries, I have proposed a standard markup structure that if adopted by thumbnail expanders and gallery backends, will remove the need for script specific glue. Perhaps the issue will eventually be solved this way? Update (2007-07-26): I am considering adding support for Lightbox2.