Could 2-clicking a word in a book or commentary have 2 actions to choose from?
1. Open the topic guide
2. Open the closest entry in a book of choice
The first one is an option now -- making the second option I am not so sure about. It would mean double-clicking a word in the book panel would actually change the entry you are viewing in that same panel.
Come to think of it, I may have a better option that could provide the same functionality. I'll give it some consideration.