Mozilla released version 38 of the Firefox web browser last week, and the updated version is available now in the Fedora repositories for Fedora 21, and for users running Fedora 22 pre-release versions. As has been the case since Firefox starting rapidly releasing new versions every 6 weeks or so, there are a handful of new shiny features, and many, many bugfixes.
Two notable new features provided by the release of Firefox 38 are the tabbed preferences, and better high DPI support.
In previous versions, the Firefox preferences were contained in a pop-up dialog box. In version 38, the preferences are now moved into a dedicated tab, much like the add-ons tab that has been in Firefox for many releases:
High DPI support
Previously, users running Firefox on high DPI screens on Fedora had to tweak a setting in the about:config to get Firefox to play nicely with their high DPI screens. Now, if the layout.css.devPixelsPerPx value in about:config is set to the default of -1.0, Firefox renders pages and its chrome at the DPI setting of the desktop. Note that if you previously followed our instructions for manually setting this value, you may want to reset it to the default by finding it again in about:config, right clicking on it, and choosing Reset