It's very good, but if i disable some search engine from Firefox option, they are always visible. The only way is to delete them. Thank you so much.

Does just what it says. All your default Firefox Search Engines presented cleanly in the context menu. You can't add search engines independent of the Firefox browser (for that you'll want Swift Search Selection), but if all you want is what's already in your address bar then this is perfection. No unnecessary permissions, no unnecessary features, what you see is what you get. Pair it with the "Add custom search engine" add-on and you have a match made in heaven.

Edit: From five to four stars because there's no way to disable the search engine shortcuts, which in turn affects how engines are displayed in the context menu.