Firefox 19, which launched in the middle of February, shipped with a built-in PDF viewer. Its successor, Firefox 20, comes with something even better - an update to the browser's outdated download manager.
Firefox 20 launched today, and the updated browser comes with a new download manager that makes Firefox much more visually appealing. If you used any previous version of Firefox, you'd know that the download manager was contained in a separate window. Now the download manager is contained within a drop down menu on the top right of the browser.
Another addition in Firefox 20 is per-window private browsing. In other words, you can open a new private browser window without having to restart Firefox.
Firefox for Android also gets an updated private window mode with the ability to open a new private tab without having to close the app. The Android app also adds the ability to customize the home screen with your most visited sites.
Finally, Firefox for Android is adding support for devices with ARMv6 processors. Mozilla says that popular devices such as the Samsung Galaxy Next, HTC Aria, HTC Legend, Samsung Dart, Samsung Galaxy Pop and the Samsung Galaxy Q all now support Firefox for Android.