I've noticed a usability issue on galleries that use the Flexible Gallery type (with Facebook-style infinite scrolling, or 'lazy loading').
If a user opens such a portfolio page and immediately clicks on the first image in the grid to open it in a Lightbox, the Lightbox will only ever scroll through the images that had loaded to the portfolio page up to that point. It will not continue to load images in the portfolio. This might often lead a visitor to believe that there were no more images included in the portfolio when in fact there may be many more....
In a large gallery with, say, 100 images, that would force a user to scroll down the portfolio and force all the images to load until the "no more images" message appears before clicking any of those images to open a completely populated Lightbox.
I would expect the Lightbox to 'lazy load' in the same way when a user clicks the right arrow to advance the slideshow and continually download images until no more are available....?
Thanks for reading!