Rated 3 out of 5 stars
This add-on is perfect for not allowing history to be deleted, however I wish it lived up to its namesake as well. While this add-on disables the keyboard shortcut for browsing privately, it does not disable right clicking the firefox icon and selecting "New Private Window." If this function was disabled this add-on would be flawless.This review is for a previous version of the add-on (126.96.36.199-signed).
Thanks for this report. I believe it is fixed in version 1.9 that I just submitted for Mozilla approval: