If you use Firefox instead of Chrome, do you do so because you prefer Mozilla\u2019s stance on privacy? Some loyal Firefox users and even employees were up in arms after Mozilla surreptitiously installed the add-on Looking Glass last week. It didn\u2019t happen to all Firefox users, but the ones affected did not give the browser permission to install it.According to a screenshot, linked from the Firefox support forum, the only description originally provided for the Looking Glass extension was: \u201cMY REALITY IS JUST DIFFERENT THAN YOURS.\u201dIts sudden appearance had the user asking if the add-on was malware. The post started a rant on Hacker News. Before long, the rant had spread to other social media sites.Although the original description for Looking Glass was both vague and cryptic, it turned out the add-on was part of a promotional campaign for the TV series Mr. Robot.In a post about the slippery-slope Firefox was on, Drew DeVault explained:This extension was sideloaded into browsers via the \u201cexperiments\u201d feature. Not only are these experiments enabled by default, but updates have been known to re-enable it if you turn it off. The advertisement add-on shows up like this on your add-on page, and was added to Firefox stable. If I saw this before I knew what was going on, I would think my browser was compromised! Apparently it was a mistake that this showed up on the addon page, though \u2014 it was supposed to be silently sideloaded into your browser!DeVault added, \u201cMozilla, this is not okay. This is wrong on so many levels. Frankly, whoever was in charge should be fired over this \u2014 which is not something I call for lightly.\u201d\u201cLooking Glass is a collaboration between Mozilla and the makers of Mr. Robot to provide a shared world experience,\u201d Mozilla later explained after users\u2019 outrage was hitting the fan. The add-on was part of an alternate reality game (ARG) meant \u201cto further your immersion into the Mr. Robot universe.\u201dExplanation doesn't satisfy Firefox users\u00a0Many users were not placated by the explanation provided in an updated description of Looking Glass, which included a how-to for turning it off. Mozilla added:The Mr. Robot series centers around the theme of online privacy and security. One of the 10 guiding principles of Mozilla's mission is that individuals\u2019 security and privacy on the internet are fundamental and must not be treated as optional. The more people know about what information they are sharing online, the more they can protect their privacy.\u201cHow can we claim to be pro-privacy while surreptitiously installing software on people\u2019s computers?\u201d tweeted Mozilla developer Steve Klabnik. \u201cMore importantly, how did management not see this as a problem?\u201dMozilla did not address the problem in its blog, instead telling media outlets that it has not compromised its privacy principles, since the add-on never collected or shared users\u2019 data and had to be enabled first before users could play the game.Yeah, well, that didn\u2019t cut it with most folks who have taken to social media to vent about how Mozilla betrayed users\u2019 trust. Then Mozilla said it planned to move Looking Glass to its add-on store so that only those who want to play, follow clues and solve the puzzle, can install the add-on. Additionally, Mozilla added the source code to a repository on GitHub.