If you are running the Firefox Developer Edition on desktop or Firefox Aurora on Android, you may have noticed a couple of changes after today's update.
Mozilla added several features to those pre-beta versions of Firefox that were previously only available in Nighly builds of the web browser.
Electrolysis, Firefox's upcoming multi-process system is advertised on first run right away. Users receive a prompt about it and may enable it in Firefox Dev if they want to.
The feature will improve the browser's responsiveness and in the long run security. The main drawback is that many add-ons are not yet compatible with Electrolysis. You can check the Are We e10s Yet website for a list of add-ons that are compatible.
The site lists 118 broken and 569 untested add-ons currently, among them popular extensions such as NoScript, Ghostery, Adblock Plus and even Mozilla's own Lightbeam for Firefox add-on.
More interesting that from a user perspective is the modified private browsing mode. You can enable private browsing with the shortcut Ctrl-Shift-P or via the menu by tapping on the Alt-key and selecting File > New Private Window from it.
The new private browsing interface has changed. It lists data and information that Firefox will forget once the mode is exited and which information it will keep.
The main new feature is Tracking Protection however. Tracking Protection blocks known trackers automatically when you are using private browsing mode in Firefox. This improves the privacy of users in that mode and has the added benefit that pages load faster in the browser.
Tracking Protection is automatically enabled. It should not be confused with an ad-blocker, as it does not block ads but only a selection of known tracking servers.
Users who don't want to use the feature can turn it off on the private browsing start page.
The third change enforces the signing of add-ons in Firefox Dev. Installed add-ons that are unsigned are disabled automatically, and the installation of unsigned add-ons is blocked by the browser as well.
The main idea behind the enforcement is to block malicious add-ons from being installed in Firefox as they cannot be signed.
Firefox Dev and Nightly editions have an override switch to enable the installation of unsigned add-ons, something that Beta and Stable versions won't support.
Additional information about all three feature additions are provided on the Mozilla Blog.