[note: see update below] This is one of my favorite extensions, but I have had problems getting it to work in recent versions of Firefox (FF52, FF53). Specifically, after drawing the rectangle around several links I want to open, nothing happens. I also tried other releases but anything in version 3+ doesn't work for me. Is there some extra step required now in selecting the links? Anyway, I uninstalled version 184.108.40.206, then went to the version history page (https://addons.mozilla.org/en-US/firefox/addon/snaplinksplus/versions/) and selected version 2.4.3 instead. Version 2.4.3 works perfectly for me. Also, I had to uncheck the "Update Add-ons Automatically" from the settings icon on the Firefox extension page so that this version would be retained in my browser. I would give 5 stars to the add-on for version 2.4.3 for the concept behind Snap Links, but 0 stars for version 220.127.116.11 since there's no obvious easy way to get it to perform correctly---so overall 3 stars (I'll update my rating if the developer explains that there's something I'm not seeing). Thanks for at least keeping 2.4.3 available as an installation option! Version 18.104.22.168 should be downgraded to beta until the bugs are worked out.
UPDATE: Snap Links worked today (5/22) in FF 53.0.3 after I uninstalled the extension and reinstalled version 22.214.171.124. I changed nothing else with my browser and its settings. Also tried the latest version in a portable copy of FF 52.1.0 ESR and that worked as well. Snap Links still doesn't work for me in portable FF 45 with the version compatible with that release, 126.96.36.199 (after drawing the rectangle around some links, it always says 0 links on any page, including a Google search results page and the Snap Links homepage), but that's an old version of both the browser and the extension so I'm not going to worry about it. Posted some info on it in the issue tracker just now, in case you want to take a look. So I'm changing my rating to 5 stars since the latest version is now working for me with the latest Firefox.