Rated 5 out of 5 stars

Firefox 34 is more careful with how XBL bindings are applied to untrusted content (see Bug 1050049 in Bugzilla). The way to make this add-on work again is actually pretty straightforward: add an attribute: bindToUntrustedContent="true" to the [binding] element in the chrome/content/focusregainer.xml file inside the XPI.

I don't use the non-lite version of the add-on, but probably the fix will be the same there.

This review is for a previous version of the add-on (0.4.1-signed). 

fixed in version 0.7