Kiwi, your plugin is very useful for tweaking covers without a full run through the Calibre conversion engine, thanks!
I've got a Penguin Classics epub that had no cover (or, I should say, I lost it after...umm...plugin processing).
The only way I could add a cover was to run conversion..and then I ended up with a broken image page called oeb_cover_r1.xhtml with a false cover (bad image path) I had to clean up.
I hope you eventually work out a "replace cover" function as you talked about a few weeks back. Sometimes it would be easier if I could just "insert cover" to a good epub that is missing one
Thanks kiwidude (and thanks for the suggestion of your plugin in one of the other cover threads).