I installed this add-on to copy a bit of text from
http://koufukuji.yokohama/analects/764
I thought at first that I had failed (and gave a two star review) because as well as prevent copying, the site changes the selected text highlight colour to a very pale yellow. This add-on works and allows me to copy text from the above page, but it would be even better if it changed the highlight colour to one which I can see for easier selection.

Absolute Winner between all of similar addons! It works even on mobile FF for Android! (but I had to request desktop version of the site, to be able to install it). Thanks a lot!

Excelente! Me ajudou muito na Faculdade que faço bloquearam o uso do botão direito do mouse no portal! Um abuso!

It's good but the "Absolute Mode" enabled messes with the search perameter on sites like movieninja.io.

很好用的一款防鎖右鍵元件，非常值得安裝使用。

Can't drag video position on Youtube, after enabling this addon. Except this drawback, everything else works, even on some websites where other similar addons are unable to show the popup.