Not working for me.

11/17/18 Not working. You can only double click on things to add them but you cannot move them wherever you want or delete them.

Pretty broken.

Can't add custom search engine, it's broken.

Pure junk. Nothing works.

Need to be able to add your custom seach engines

Try https://addons.mozilla.org/ru/firefox/addon/selected-text-searcher/
This addon hasn't been updated since the release date.

Sorry but, I cannot get this works. I configure the drop zones and it could not be saved. This complement is so useful that I will really miss its lost