Yes, after digging around and googling, I came to understand what the *intent* was for this field/drop-down menu. I tried to replicate it myself (by making a gallery and setting the drop-down menu, then making an album and dragging the gallery into it), but when I previewed it, I got the ‘no images were found’ message.
It appears that there may be a bug in the code(?) because on the documentation page it appears to be broken also:
Look at step 2 under ‘ADD ALBUM TO PAGE/POST’, where it says, “Compact will display like this:” and “Extended will display like this:”
Regardless — I am still curious to know how hard it would be to ‘hack’ this in order to add new functionality as I describe above. If we could use source=”pageid” then I think it would make it very easy to create custom per-page galleries, but only have to use one generic shortcode in a site-wide primary sidebar to display those thumbnails. Can you offer any help or suggestions?
Thank you!