Works somewhat. I added google translate and had to set it to open in a new tab, otherwise it wouldn't work (a green prompt). As of now I can double tap a word and it will open in google translate, but the annoying prompt is still there.
I use Android.
To conclude, three stars.

howto make it works in input text area?

Prevents you from selecting a text and using right click (to copy it or search for in the Google).
The dictionary itself works good.

Using it on Firefox Android, some time tapping ousite the popup wont close it, so sad! :(

I don't know if it is just with me... but I've tried to add a dictionary... fill in all fields but when I push "add"... nothing happens, at all!