With this RSVP plugin active, the new WP 3.5 Media manager breaks. I cannot select images that are already part of the library. Image thumbnails cannot be checked on or off, and the Media Manager window cannot be closed. The page has to be reloaded, loosing any unsaved edits.
I cannot upload new images using the drag & drop tools. When I try, the first image is loaded in the browser window instead of being received by the WP Media Manager.
I have figured this out by deactivating all the plugins on the site and selectively turning them back on until I recreated the error.