The tab bar is placed atop the address bar (you can also revert this setting), resulting in a more polished, cleaner appearance. If you’re like me, you keep dozens of tabs open as you scrub through your favorite websites. This quickly adds up to the confusion as sorting through tabs becomes an increasingly tedious affair. Luckily, more controls are now available to manage your tabs.
A new button in the upper right corner next to the address bar launches a brand new tabs management interface called Panorama. If the icon is missing, customize your Navigation Toolbar by dragging the Tab Groups icon on the Firefox toolbar area. Panorama lets you group tabs by dragging their thumbnails around, save and rename groups, tuck them away, and peek inside stacks. You can also pin tabs to prevent accidental closing, search through open tabs right from the address bar and more. It’s a welcome addition that the fans of heavy tabbed browsing will undoubtedly love, especially those multitasking on several projects at once.
Expanded privacy controls are available in the Options menu, allowing you to fine tune which web sites are allowed to use tracking cookies. Firefox’s add-ons manager has been re-worked and Firefox Sync is now part of the browser rather than an optional add-on. Firefox Sync is Mozilla’s technology that keeps your browser settings, bookmarks, history, passwords and other data synchronized across desktop and mobile devices running Firefox.
Firefox Release candidate for Maemo and Android is also available for download. Also worth mentioning, Windows and Linux versions of Firefox 4 remove the menu bar and put frequently used options under the new orange Firefox button in the upper left corner of the window. You can re-enable the regular menu bar anytime in settings.