Just "discovered" this. I'd been trying to create a Skylist of easy doubles (many of the published lists are too much for my spotting 'scope), but after a bit of messing about on a PC trying to create a Skylist file that SS5 could read I realised I could just use Advanced Search to do it all for me. Hurrah!
Minor quibbles - could you position the "make into observing list" button at the top of the advanced search results list rather than the bottom, saves a lot of scrolling! And could you let the user enter the name of the list rather than just using "Search Results" (or whatever it was) as the name?
