The Mozilla Firefox developers are working on several different branches of the web browser at the same time. The latest public version, Firefox 3.6.6 just released today, and Firefox 3.7 which will be renamed to Firefox 4.0 later this year.
The latest nightlies of Firefox 4.0 concentrate on finalizing the graphical user interface of the web browser. We have reviewed some design changes like tabs on top or Windows Aero support in the past.
Chrome and Opera users will recognize many similarities, many Firefox users on the hand will need some time to get used to those changes.

firefox 4.0
The most obvious user interface changes are visible in the Firefox header. The menu bar has been reduced to a Minefield button which displays the menu items on click.
Tabs are not on top of the address bar by default. That’s again similar to how Google Chrome and Opera display the tabs.
Both options can be reverted by customizing the top bars in Firefox. The menu can be expanded and the tabs placed under the address bar. It remains to be seen if those options will be available in the final Firefox 4.0 release as well.
Firefox users who have placed other UI elements in the menu bar in previous versions will notice that they are automatically hidden if the single menu button is active. A bookmarks bar placed in the menu toolbar for instance is not visible in the default design. Lots of free space in the main toolbar which could be put to good use.
The title bar has been removed, page titles are now displayed in the tabs only.
The navigational elements fit nicely in the design. The arrow symbol next to the forward and backward buttons provides a listing of the last opened tabs in the web browser.
New buttons can be added to the toolbars as well, available are for instance buttons to display the bookmarks or download manager.
Windows Vista and Windows 7 users will notice that the Aero implementation is still not optimal depending on the background colors. A dark background image makes the displayed menu bar items almost unreadable.

firefox 4 windows aero
The graphical user interface nears completion but it is likely that it will be fine tuned by the developers to sort out the latest quirks before the beta versions and release candidates get released.
The reveamped add-ons manager is another new interface element in Firefox 4.0. The manager displays in a tab in the browser now and displays the standard options to manage add-ons, themes, plugins and to get new add-ons.

firefox 4 addons manager
Firefox users who want to test the latest Firefox 4.0 builds can download it from the locations below for their operating system:
firefox-3.7a6pre.en-US.win32.installer.exe
firefox-3.7a6pre.en-US.mac.dmg
firefox-3.7a6pre.en-US.linux-i686.tar.bz2
What’s your take on the new Firefox design?
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New tab position is welcome.
Keeping an option open will likely be appreciated by many users.
Not much into personas so, if they can still allow my favorite Littlebird addon as theme, then that will be just fine for me.
This is even better than the Tiny Menu extension.
I’ve updated to the latest Minefield version but it’s not showing the new ui changes?
Thanks Martin . Firefox 4 will be the best browser ever ! or at least that’s what I think :) . Google Chrome crashes a lot even in stable versions and Opera is just too complicated so that makes Firefox the winner :)
Same asStormtrooprDave, I don`t get Minefield button… Martin help us or any other member….
If you do not see it you have to right-click the toolbar, select customize and disable the Menu bar.
Looks like Internet Explorer. Way to innovate, Mozilla!
Actually looks like Chrome. Hate these changes. Will not be updating until all userstyles are ready to make it more acceptable.
On XP my minefield button appears on it’s own line between the title bar and the address bar. Looks dumb sitting there by itself. If XP doesn’t support putting it up in the title bar then whack it on the end of the address bar line.
Loading on Debian GNU/Linux Sid with KDE 4.4.4, this disables all of my current addons and themes, and also has a LOT of icons at the top-right of the screen that don’t do anything except drop-down my bookmarks. The icons are all the left/right/stop/reload/home/downloads… icons, repeated over and over…
> and also has a LOT of icons at the top-right of the screen that don’t do anything
> except drop-down my bookmarks
Turning on the Bookmarks toolbar removes these icons. Not exactly what I wanted, but better.
Looks like firefox really inspired by the chrome. I expected firefox team to be more creative
I didn’t liked new addons manager. It is just over-sized, without providing much info, maybe good for beginners, but there should be an option to have “classic” windowed one. Also it doesn’t work with All-in-one-sidebar, which is the most inconvenient thing for me in the new design.
Hope to have more profeesional design solutions in Firefox, not just copying from Chrome( which i don’t think is better just beacause of simplicity) or trying to look *COOL*(like in addon manager case).
I want Firefox to be MY browser, PERSONAL.
Overall not impressed with new design chnages, need more creativity.