Doesn't really work Rated 2 out of 5 stars

Manko / Disadvantage: The icon button with the little f for the Facebook logo above the sort of character like ⩒ in blue doesn't appear on the toolbar beside of other icons here

This review is for a previous version of the add-on (1.1.4). 

Icon

a fix has been made and submitted to the Firefox team to review it. Thank's for the feedback.