It doesn't work. It did when I first started using it, and even then it gave no indication of whether or not a tab was loaded. The problem has persisted through the last update, too, so I'm not sure what's going on.
Work like a charm! Finaly there is one that work with ff 58. You save my day man. By the way could you can make a keyboard shortcut or a button to unload tab. Expect on next release. Thanks and regards.