Webextenstions version drops features Rated 1 out of 5 stars

The selection interface of this version is absolutely, unbearably slow. I actually have to drag the mouse very slowly in order for it not to "lose the grab" of it. I want the old version back!

No longer able to set default directory, which is a MAJOR drawback for me. I don't care about webextenstions API not letting you do this, either convince the FF devs to add this, or DON"T switch to webextensions API. If none of the addons devs would switch and none of the users would update to 57, the FF devs would revert their stupid decision.

This review is for a previous version of the add-on (2.2). 

> The selection interface of this version is absolutely, unbearably slow

This error appear for not all users and depends on the version of Firefox
wait for Firefox 57 release in November 2017

> No longer able to set default directory

this limitation of WebExtensions

WebExtensions - this is the inevitable change in Firefox - all Xul-addons will die out in Firefox 57
https://blog.mozilla.org/addons/2017/02/16/the-road-to-firefox-57-compatibility-milestones/

But you can install Firefox 52 ESR and enjoy work XUL-addons until June 2018
https://www.mozilla.org/en-US/firefox/organizations/faq/