Hello,
Thought I would give the 2.5.4 Essential theme a try, but have encountered two problems for your review and comment.
Here is the first, concerning the Book Module. The other is in ddmarker and will follow in a separate email.
The attached Book Module screen shot tells it all. The Table of Contents appears over the image area for the book page and is not draggable from this location. I checked it in Clean theme and it can be drug to the right column. Also draggable in Standard theme.
I did completely remove Essential 2.5.3 before adding 2.5.4.
Let me know if I should submit this as a bug or if there is some solution I am missing.
Regards
Rod