Remove the CTRL + UP and CTRL + DOWN shortcuts Rated 4 out of 5 stars

Please remove the CTRL + UP and CTRL + DOWN shortcuts (or introduce one option to activate/deactivate these shortcuts).
The reason of that, is because these shortcuts are already used to change the "Search Engine" when the cursor are on the search box of firefox.

Apart from that detail, this is an excellent extension.
Thanks

This review is for a previous version of the add-on (2.2).