Really really valuable add-on. I need it and I've got it :) Works very wonderfully too...I just installed and wrote a very excited review for another add-on that may be an earlier version of this called 'Extended link properties +'. Not the same as in your link above. This one has same icon and same look as your present one, but only one tab in options panel. and the ominous word "(obsolete)" after title on add-ons page. https://addons.mozilla.org/en-US/firefox/addon/extended-link-propertie-124503/ Also a different developer name. So I disabled that one when I found and installed yours. Since that one is said to be no longer in development, I extend all kudos and gratitude written there to you and this present and updated and currently maintained version.
This review is for a previous version of the add-on (188.8.131.52-signed).
See "Developer’s Comments" for Extended Link Properties +: https://addons.mozilla.org/addon/extended-link-propertie-124503/#developer-comments
Extended Link Properties + is a bit modified version of my old (unofficial) fork (based on version 1.4.0): https://forum.mozilla-russia.org/viewtopic.php?pid=479897#p479897 (was changed only extension ID and localization)