I can't get this working. I can get the Xray button to show up, and when pressed it displays a list of terms/characters, but whichever one I press I get a garbled line like:
"enc type="toc" title="Table of Contents"
I tried on a Paperwhite running 5.3, a Paperwhite running 5.2 and a Touch. I've tried on a side-loaded book AND an emailed Personal Documents one. Same result every time.