Now that we are talking custom comments.
Here's another issue I noticed. I have two custom comment fields and also changed the order of the fields shown in the metadata editor's custom tab. Don't know if this fact is related to the issue though.
When using the Metadata editor (single book mode) and using the previous/next buttons. The 'html source' tab of a custom comment gets out of sync with the 'Normal View'
It does not matter if I have the html source tab or the normal view tab focussed.
It always switches away from the html source tab to the normal view tab anyways when using prev/next and when I then switch back to html source, I always see the html source of the first book on which I opened the metadata editor, as if it got stuck