Absolutely Terrible Rated 1 out of 5 stars
I can't seem to give less than 1 star, 1 is to high for this.
There is a sidebar with this that constantly pops up, not just while viewing a CHM file, it pops up when browsing, or opening a new tab or clicking links, it's even popped up and vanished a few times while typing this. Selecting some of the text I'm typing makes it pop up or vanish each time.
The dev uses keyboard shortcuts that can't be changed, and happen to conflict with my global keyboard shortcuts so they don't work, great example of the poor practice in the workings of the addon.
Each time I click a link while viewing a CHM file it opens the save dialogue box asking if I want to save some strangely named file, where it says "You have chosen to open" it shows some HTML source of the CHM being viewed.
It's just horrible.
This is the poorest implementation of a worthwhile feature I can remember ever seeing.