Hi, Before upgrading, one feature of the Preview app that I used very regularly was the sidebar, which shows thumbnails of all the pages in list order. You could use this to move pages around, and even insert new pages into PDF files. I haven't been able to get this kind of behavior to work in Mountain Lion. The Sidebar menu item is greyed out no matter what file I open. Am I missing something, is it just a problem with my installation, or was this feature removed? Any ideas?