A nice add-on that does only the one thing it's meant to but this is done very good. And no third party software needed anymore where different APIs can be used.
Only the shortcut does not work for me, it always opens the Firefox library (German keyboard layout) and I experienced some glitches in online forms: when I entered text and then hit backspace the former text was still visible and new text was simply written over it which was pretty unreadable - turning off this add-on removed this behavior and turning it back on brought back the error so i suspect it's this add-on. Would be 5/5 if the key combination could be changed and the text glitches were gone.