Mockup screenshots of a new default Firefox theme have been uploaded by Stephen Horlander to his Mozilla website. The new user interface goes by the name of Australis according to the file names of the images on the ux presentation page.

The majority of screenshots show the Apple Macintosh version of the new theme, while only two show how it would look like on PCs running the Windows operating system.

The following mockup shows how the new theme would look like on Windows versions of the Firefox browser.

The next how it would look like on a Mac.

Interested users find all mockups on the presentation page over at Mozilla.

A major change is the integration of the Firefox menu button in the tabbar. This moves the first tab to the right of the interface. The active tab is now displayed with rounded corners, while all other tabs are displayed directly on the background of the web browser and not on an inactive tab background.

A Deviant Art user has created a theme for the browser that mimics the mockup. The theme is only available on Deviant Art and not on the official Mozilla website. Interested Firefox users can download them theme from this page or at the official Firefox Add-On repository over at Mozilla.

No compatibility information are provided on the page. It is likely that the theme is compatible with all versions of Firefox that use the new menu bar button, which would mean all versions from Firefox 4 on.

How do you like the new theme? Let us know in the comments. (via)

Hacking the style files on the other hand is not something that every user can do nor wants to do. That’s where add-ons like Theme Font Size Changer comes into play. Add-ons are another – more convenient – way of changing Firefox elements and styles.

This particular add-on changes the font size of the Firefox theme. Firefox theme in this regard means all interface elements that display text including tabs, menus, status bar, address bar and other toolbars and even the context menu of the browser.

The add-on places an icon in the Firefox status bar that will open the font size selection menu when pressed. Selecting a new font size will instantly change the size of all Firefox interface elements to the selected size.

The font size selector offers one entry to reset the font size to the normal one used in Firefox by default. This is helpful in case the changes turn out to make interface elements inaccessible or unreadable.

Theme Font Size Changer can be downloaded from the official Mozilla Firefox add-on repository.

I make use of core add-ons that are installed all the time and temporary add-ons that I only install when I need them. Two examples for temporary add-ons are the excellent web development add-on Firebug and the multi-site video downloader Video Download Helper.

I also have to say that I’m running the latest version of Firefox 3.6 and not the latest stable version of Firefox 3.5x. Many of the add-ons had to be forced to be compatible with the Nightly Tester Tools add-on. They do work perfectly though afterwards.

• App Tabs – I reviewed the add-on yesterday and really like it. Tabs can be pinned and minimized on the left side of the Firefox tabbar. This is great for websites and services that are open all the time.
• Bug489729 – This prevents Firefox from opening a new window if a tab gets dragged accidentally in the web browser. Some users do not have a problem with this at all while others have to cope with this behavior regularly.
• Greasemonkey – Userscripts can be very useful in many occasions. There are some great ones out there that really improve the web surfing experience.
• Last Pass – I switched to Last Pass after using the build in Firefox password manager for a long time. Last Pass offers a lot of additional features including a secure password generator, form profile manager to automatically fill web forms, automatically log into websites, web access to all passwords.
• Multi Links – If you regularly work on websites where lots of links are posted that you all need or want to open then Multi Links is for you. You can draw a rectangle around an area on the website. Every link in that rectangle will be opened once the user lets go of the right mouse button. Excellent for forums, link lists or blog posts.
• Nightly Tester Tools – Most add-ons have not been updated by their developers yet to be compatible with the Firefox 3.6x branch. This tool makes them compatible with this version. It will be uninstalled once all developers have updated their add-ons.
• No Redirect – If you hate being redirected by your ISP to a search page whenever you mistype an url then this is for your.
• NoScript – One of the two Firefox add-ons that I consider most important (the other is Last Pass). No Script will block all scripts from being executed on a website on the first visit. This increases the security of the web browser and computer system as most exploits and attacks make use of scripts to do so.
• SeoQuake – Useful for webmasters. SeoQuake can display various SEO related information about websites including their Pagerank, links, Alexa rank and more.
• Tiny Menu – I like the Firefox header to be as small as possible so that the actual website makes use of most of the screen estate in the web browser. Tiny Men compresses the menu into one menu entry which can then be merged with the address bar so that only one bar is shown at the top of the web browser.
• Operetta Theme – I ran the default Firefox theme for most of the time. But then I discovered the Operetta theme which brings the design of Opera 10 to Firefox. It looks fabulous but only works with Firefox 3.6x versions.

And that’s it. Not a lot of add-ons if you consider that some Ghacks readers use 70+ add-ons.

The Operetta theme comes in two versions, a normal and advanced version, which differ mainly in the toolbar layout. Both Operetta themes are based on the design of the Opera 10 web browser with the normal version making use of the standard toolbar layout with tabs below the other toolbars and the advanced version placing the tabbar above all other toolbars.

Both editions of the Firefox theme look professionally done and the selection comes down to the personal preference of the user. Some Firefox design mockups suggest that the developer’s are thinking about moving the tabbar to the top of the web browser header and the Operatta Advanced theme for Firefox can be used to get accustomed to this possibility. It might also be the prime choice for Opera or Google Chrome users as these web browsers place the tabbar by default above most – in Google Chrome’s case all – other toolbars. The Operetta and Operetta Advanced themes are available at the Mozilla Firefox website.

The theme is no longer available on the official Firefox themes website. An alternative is the Fopera theme.

The Strata 40 theme for Firefox is probably the most complete theme yet as it combines not only a Firefox theme but also add-ons and userscripts that need to be installed to look like the Firefox 4 design mockup. Several versions of the theme are possible depending on the add-ons and scripts that are installed next to it. This somewhat reflects the various designs that have been posted by the Firefox designers (e.g. tabs on top or normal position for tabs).

Links to all add-ons and userscripts that are needed to make the theme look similar to Firefox 4 designs are posted on the theme’s page at the Mozilla website. Here is the list for your convenience:

• Download and install the Strata 40 theme.
• Install Strata Glass add-on for glass effects in Windows Vista and Windows 7. [optional]
• Install Personal Menu add-on for Bookmarks and Tools buttons in the toolbar. [optional]
• Install Fisson add-on for progress line features. [optional]
• Install the Stylish add-on and the Tabs on Top userstyle to move the tabs to the top of the web browser. [optional]
• Install the Omnibar add-on to add search functionality to the address bar. [optional]

The result is a elegant theme for the Firefox 3 web browser.

It might take some time to get used to the new Firefox theme as it changes the display of the tabs quite a bit to gain as much screen estate as possible. The theme is also changing many of the icons including those in the navigation toolbar of the web browser but also scrollbars and other elements.

New themes do not always support all Firefox extensions. The software developer has taken extra care by ensuring that the Firefox theme is compatible with dozens of popular add-ons. The Littlefox theme is ideal for users who want to save screen estate. Might be ideal to run on a netbook where vertical screen space is limited. The downside is that the theme is not visually stunning at all but that is also not the purpose of it.

Some of the changes can also be achieved in other ways. You could check out our Setup Firefox To Use Minimal Screen Estate for some pointers on how to do that.