Given that FAQ 64 doesn't mention the current need to enter ALL information in the mood theme editor... and that we still get requests wondering why the darned thing won't save, might it be a good idea to mention it? Should just need to add something like:
Please ensure that you enter the URL, the height, and the width of each image that you wish to use in your mood theme.
... or would it actually probably be a better idea to just add it at the top of the "Editing Theme [FOO]" page at http://www.livejournal.com/manage/moodthemes.bml?