No longer works at manualslib.com. The support site is inaccessible [403 error].

Had to create a Firefox account just to rate this extension. I've used it so much and could no longer imagine being without it (browsing using other people's PCs feels like a pain now). Like earlier reviewers have said it really should be a default shortcut in Firefox (and other browsers too). I'd give 6 stars if I could.

This deserves to be a recommended addon

it works as expected!

Doesn’t work on my Firefox Quantum 57.0 :-(

Great!

It's should be in firefox shortcut by default.
Thank you, save a lot of time.

Used to work great until the last version from April.

Since you don't have a bug report site, I'll drop mine here:
the addon has never worked after April's release, no inputs get focused or cycled.
For an example, test http://webster-dictionary.net. BTW from a quick inspection that site uses iframes.