Firefox 4, or more precisely its only update Firefox 4.0.1 was released April 28, less than two months ago.

Firefox 5, which has been released yesterday is seen by Mozilla as a security update for Firefox 4. It in turn means three things:

• Mozilla Firefox 4 users will not get any more updates
• Firefox 4 users who have not updated yet are running a browser with security vulnerabilities
• Support for older versions of the browser has been reduced significantly

Some users might say that it is not all that bad. Just update from Firefox 4.0.1 to Firefox 5 and you are protected again, and update again from 5 to 6 and so on. Some arguments speak against this practice. Enterprise users need to do a lot more testing because of the new release process, and users who came to rely on specific add-ons, might have to disable them or force compatibility on them to get them to work in the next major version of the browser.

Mozilla notes that the major version updates are typically less likely to cause incompatibilities and other problems, due to the rapid release process which pushes out smaller releases regularly instead of big releases occasionally.

One thing that I’m personally a bit confused about is whether automatic updates are applied to Firefox 4, or not. I installed a test version, and while it shows a new update for the browser under Help > About Firefox, it does not seem to apply that update automatically when I close the browser and open it again. The Aurora release on the other hand applies updates automatically on every start.

Does that mean that Firefox 4.0.1 or 4.0 users are not getting Firefox 5 delivered as an automatic update? If that is the case, does it mean that Firefox 4 users are running a browser with known security vulnerabilities?

If you are running Firefox 4, I recommend to update to the latest version of the browser immediately.

What’s your take on all of this? Let me know in the comments. You can read the lifecycle policy discussion here at mozilla.dev.planning.

Content Security Policy has been in development for quite some time.. The basic idea behind the standard is to give webmasters a tool at hand to whitelist JavaScript, and other objects and files, that may be executed on the site. This implementation blocks all JavaScript code that is executed on the site and not in the list of allowed sites, which means that attackers cannot exploit possible XSS vulnerabilities on the website or server.

A browser supporting CSP ignores code that is not in the whitelist. Browsers who do not support CSP ignore the policy.

Content Security Protection for Users

CSP is currently only supported by Firefox 4, Thunderbird 3.3 and SeaMonkey 2.1. You can test the functionality by visiting this test page.

Twitter recently announced that they have added CSP to their mobile version, accessible under mobile.twitter.com. Users who use one of the aforementioned browsers are protected from XSS attacks on that website.

The engineers on Twitter removed all JavaSCript from code and implemented the CSP header. They then restricted the header to Firefox 4 users and created a rule set to allow JavaScript from their assets. This included the content deliver network used to deliver stylesheets and user profiles.

Unexpected issues were encountered by the developers. They noticed for instance that some Firefox add-ons were inserting JavaScript on page load, which triggered a threat report. The Twitter engineers noticed furthermore that some ISPs inserted JavaScript code or altered image tags for caching reasons.

They managed to resolve those problems by mandating SSL for all Firefox 4 users who access the mobile Twitter web site.

A test with Firebug shows that the mobile version of Twitter is indeed using the policy on site. Please note that Twitter makes a user agent check and is very restrictive about it. Firefox 5 or Firefox 6 users won’t get the policy currently.

Content Security Protection for Webmasters

Webmasters may have some work at hand to add support for CSP to their website. JavaScript code that is directly embedded in documents will not be executed anymore, which has several implications. Webmasters need to move the code to external JavaScript files.

Policies are specified with the X-Content-Security-Policy header. The header X-Content-Security-Policy: allow ‘self’ *.ghacks.net for instance allows JavaScript to be loaded from ghacks.net and all subdomains of ghacks.net.

The using CSP guide on Mozilla offers additional examples on how to set the right headers.

Browsers that do not support CSP ignore the header.

CSP offers two additional forms of protection. It mitigates clickjacking attacks. Clickjacking refers to directing a user’s mouse click to a target on another site. This is often done by using transparent frames on the original website.

Content Security Policy can also be used to mitigate packet sniffing attacks, as it allows the webmaster to specific protocols that are allowed to be used. It is for instance possible to force HTTPS only connections.

The CSP Policy directives are accessible here on Mozilla.

Next to the already mentioned options are parameters to specific hosts where images, media files, objects or fonts may be loaded from.

Plugins are available for WordPress and Drupal that add the policy to supported websites automatically when activated.

Bookmarklet

A bookmarklet has been created by Brandon Sterne to aid webmasters in defining the correct header. It basically scans the page for JavaScript and displays a suggested policy.

Issues and Concerns

The biggest problem currently is that CSP is only supported by Firefox 4. Not by Internet Explorer, Chrome, Opera or Safari. But even if it would be supported by all browsers, it would still depend on webmasters to implement the headers on their websites.

A push in the right direction could come from Twitter, if the decision is made to role out the CSP header to the main Twitter web site as well.

The beta release notes classify Firefox 4.0.1 as a security and stability release. Bugzilla lists a total of 53 bugs that have been fixed in the latest Firefox release. Of those, 12 have received a severity rating of critical, another 9 one of major.

The majority of critical issues have been crash and freeze related, only two address other issues. Other notable fixes include a issue where Adobe pdf documents with a size larger than 5 Megabytes could not be loaded in the browser, problems with the address bar and other text edits after loading pdf documents using Adobe Reader X and the inability to refine searches on Yahoo answers.

It can take up to 24 hours before the release is officially announced on the homepage and via the browser’s built-in updating functionality. It is likely that download portals such as Softpedia or Major Geeks will be faster and offer the download on their sites before the official announcement.

Since it is a security release it is important to update the web browser as soon as possible. A good starting point is the official Mozilla Release Mirrors listing which often provide access to downloads for all languages and operating systems before the final release announcement on the Mozilla Firefox website.

The release notes are accessible here.

The following collection of tips is specifically for users who have little or no Firefox 4 experience. That said, it is likely that some tips are new even to veteran Firefox 4 users.

1. Where is the page history?

Firefox 3 displayed a small arrow next to the previous page and next page buttons in the main Firefox toolbar that listed previously accessed web pages. This button is not there anymore in Firefox 4. The functionality on the other hand is. A right-click on either button displays the page history again so that it is still possible to open one of the pages of the history.

Please note that Firefox keeps individual page histories for every open tab.

2. Blurry Fonts

If you have sharp eyes you may have noticed that the fonts are kinda blurry in Firefox 4. I’m not sure why it is blurry, but most users assume that it is bug that will be resolved in a future version. This is fixed by disabling hardware acceleration in Firefox. This is done with a click on the Firefox button and the selection of Options from the context menu.

Hardware acceleration can be disabled under Advanced > General. The option is called Use hardware acceleration when available.

Please note that deactivation may reduce performance for some web applications.

3. Missing menu, status bar

The developers have replaced the menubar with the Firefox button. It is possible to undo the change. A right-click on free space in one of the toolbars and the selection of Menu Bar switches back to the old layout. Users who only need to use the Menu bar from time to time can press Alt to display it temporarily.

The status bar has been removed completely. A new bar has been added that is now called the add-on bar. The add-on bar can be added to Firefox in the same fashion. It is placed in the same location as the old status bar and offers much of its functionality, including the display of add-on icons and information.

4. Moving, Adding, Removing Buttons

The customize option in the very same menu offers several interesting options. Many screen elements, like the navigational buttons for instance, can be moved around in the interface once customize has been selected. Even better, it is possible to add new buttons from the selection menu, or remove buttons from the interface that are not needed.

Some interesting buttons that can be added are print and bookmarks.

5. Tabs on top?

Firefox displays tabs on top by default which is a big change for Firefox 3 users. The customize menu has an option to move tabs back down. The entry Tabs on top needs to be unselected to move them below the address bar again.

6. My favorite add-on is not compatible

Add-ons that worked in Firefox 3 may not be compatible with Firefox 4. This sometimes does not necessarily mean that they are incompatible, only that the developer has not updated the compatibility information of the add-on yet. Firefox 4 on the other hand blocks all incompatible add-ons regardless of the reason.

A configuration parameter overrides the add-on compatibility check for all add-ons. Here is how you add it to the browser.

Select the address bar, type about:config and hit enter. Right-click and select New > Boolean. Enter extensions.checkCompatibility.4.0 as the name and False as the value. This overrides compatibility checks in Firefox 4. You can set the value to True at any time to enable compatibility checks again.

7. Your tips

Feel free to share your tips in the comments.

The release is currently available on the release server, and various mirrors throughout the world. Most mirror servers and the original Mozilla server block the download of the new release. One that does not is the server of the Umea University in Sweden. Just scroll down to Europe and click on that server to download the release candidate early.

The release notes page has not been uploaded yet. Users who have updated to or installed Firefox 4 will get a page not found error. It is likely that Mozilla will enable automatic updates and the release notes page in the next 24 hours.

Users of the beta of Firefox 4 may need to make a change to the Firefox configuration, if they have used it to override add-on compatibility. They need to write about:config in the address bar and hit the enter key on the keyboard.

The new setting to override add-on compatibility in Firefox 4 can be added with a right-click and the selection of New > Boolean from the context menu. The new value’s name is extensions.checkCompatibility.4.0 and it needs to be set to false.

Firefox 4 will not check an add-ons compatibility with the parameter set to false.

I will update the article when the downloads and the release notes page go life. (via)

Update: Mozilla has published the What’s New Page and the release notes. The release notes state the Firefox 4 contains “general stability, performance, and compatibility improvements”. The list of fixed issues contains several hundred entries and is accessible here. The release notes page lists the downloads for all Firefox 4 RC versions.

The website currently links to beta 11 which eventually will be replaced with the download link to the newest beta of Firefox.

The Firefox 4 Beta 12 changelog has been posted and it lists several of the more “popular” improvements in this version of the web browser:

• Increased performance while viewing Flash content
• Improved plugin compatibility with hardware acceleration enabled
• Hovering over links now displays the URL at the bottom of the window rather than in the location bar
• General stability, performance, and compatibility improvements

One interesting change is that link hover information have been moved back down just above the Firefox add-on bar and almost exactly like Google Chrome and other browsers display those information.

Firefox users who access multimedia contents will benefit from performance and stability gains in the latest beta version.

The full Firefox 4 Beta 12 changelog lists hundreds of changes and fixes, all linking to a Bugzilla error reporting page.

The majority of Firefox ftp and http mirror sites appear to host the new release already. Interested users can take a look at the mirror directory to download the release before the official announcement on the website.

What are the next steps? The team builds the Firefox 4 Release Candidate which is likely to ship in the beginning of March. Eleven hard blockers are left that need to be fixed in the coming builds. The final release will follow suite soon thereafter, provided that no serious issues are discovered in the meantime. (via)

Interested users can take a look at the Firefox 2011 Roadmap Updated, Expect Firefox 7 in 2011 and our guide Firefox 4 Essentials: What You Need To Know Before Making The Switch that prepares users before they make the switch to Firefox 4.

Asa Dotzler confirmed yesterday that Firefox 4 Beta 12 “went to builds” on February 22. He furthermore mentioned that “this final (!!!) beta contains fixes to more than 200 hard and soft blockers”. The important word here is final which means that beta 12 will be the last beta before the release candidate.

He notes that there is still some patching to do for the release candidate build, with 26 remaining blockers of which half “have patches in some state of evaluation”. Mozilla has not yet revealed a release date for the final beta, release candidate and final version of Firefox 4. It is however likely that the beta will be available in the coming days, maybe even today.

I let you know once it becomes available so that you can update your beta versions of Firefox 4 to the latest as quickly as possible. Asa posted an interesting link in the newsletter pointing to Facebook’s updated HTML5 games benchmark which sees Firefox in the lead followed by Microsoft Internet Explorer 9 and Google Chrome. Opera and Safari follow with a big performance drop. The reason? Hardware acceleration. The three browsers that lead support hardware acceleration, while the other’s do not at this point in time. Opera however has already mentioned that they plan to integrate hardware acceleration in a future version, and that it will support at least the Windows XP browser as well.

Back to Firefox. If the developers stay on track it is likely that we will see a final release of Firefox 4 in the first half of March 2011.

Mozilla notes that there has been a “huge increase in daily comments about memory and CPU usage” and that users reported that Beta 11 of the Internet browser felt slower than Beta 10.

The feedback summary lists several heavily reported issues, from constant reloading on Hotmail and Flash related crashes on Facebook games and Gmail over font rendering issues on Windows and Gmail lock ups to the inability to switch search engines and broken Facebook chat.

A closer look at individual user feedback shows that some users have experienced memory usage of up to 1.4 Gigabytes and 100% cpu usage. The majority of users are however reporting memory usage of a few hundred Megabytes.

It is not clear yet how the team will react on the increase in reports. Mozilla aims for a March release of the final version of Firefox 4, a doable task with only 8 open blockers left of which seven have a patch ready. The performance and stability issues on the other hand could in worst case postpone the release of the browser once again.

The coming days will show how the developers react: Will there be another beta or will they be able to fix the issues in the release candidate of the browser?

Have you worked with the latest Firefox 4 beta? Let us know what you think of it.

In his blog post he basically comes to the conclusion that Internet Explorer 9 is not a modern web browser. The conclusion is that IE9 supports less web standards and less technologies than Firefox 4 and can therefor be considered “More modern, but not really modern”.

One of the arguments brought forth describes how Firefox 3.5 supported technologies such as video and canvas tags years ago while Microsoft added support for these technologies only recently.

This raises a question from a user perspective. How many websites actually used those tags two years ago? The same questions can be asked for HTML5, CSS3 and JavaScript Api compatibilities.

Are users actually benefiting from the additional 125 points of Firefox 4 in the HTML5 test or is the majority of users never going to visit a website that makes use of those tags? What if Microsoft plans to add support with the first major update of IE9?

The official transition to HTML5 will be in 2014 and while some web developers are already making use of HTML5 technologies the majority of websites do not require the technology yet.

Another interesting aspect of comparisons is to look at the things that are not mentioned or included. No mentioning of the Acid3 test? Probably because the values are to close (IE9 95%, Firefox 4 97%). No mentioning of JavaScript performance? Maybe because Internet Explorer 9 is a tad faster, albeit not much.

I think that Firefox 4 is a great browser and the developers should not feel the need to point at other browsers to show that. Internet Explorer 9 is another great browser, a huge step forward compared to Internet Explorer 8. Office users who are stuck with IE8 will sing out in joy when the system admin updates the browser. It is faster and offers better compatibilities.

What’s your take on the infographic and blog post?

The Tell Web sites I Do Not Want To Be Tracked option is an opt-in option which means that it is disabled by default. Firefox 4 Beta 11 or newer users find the option under Tools > Options > Advanced. It is not clear why it has been moved to the advanced tab and not the privacy tab where it feels more natural.

The feature activates a Do Not Track header that will signal websites that the user wishes to opt out of behavioral tracking. Websites have to interpret the header correctly and advertisers need to abide by it for it to have a positive effect.

The second change is only visible in pre releases of Firefox 4 Beta 12 or later. Mozilla has finally changed their mind and moved the link url information from the Firefox 4 address bar back to the bottom of the browser screen. The urls are now displayed in a Google Chrome like fashion in the lower left corner of the screen. Users who have the add-on bar enabled will notice that the link information are posted above the toolbar.

The move is definitely a step in the right direction considering that felt alienated by the decision of the development team to move the information in Firefox 4 to the address bar. It is interesting to see that the team is reverting some of the design and interface changes they did introduce in earlier development builds of the browser. Interested users can download the latest official beta from the Mozilla website.

Extension Options Menu is a Firefox add-on that provides quick access to all option pages and windows of installed Firefox extensions.

A new entry is added to the Tools menu by default which offers faster access to the extension configuration pages.

A click on an entry in the new context window opens the options page or window in the web browser. It is furthermore possible to add quick access to the options menu to one of the Firefox toolbars. This is done by right-clicking free space in one of the visible Firefox toolbars and selecting Customize from the options in the context menu.

A new window opens with icons. It is now necessary to locate Extension Options (should be located near the end of the listing) and drag and drop the icon to the desired location in one of the toolbars.

Placing the icon in one of the toolbars improves the accessibility further, as it is now possible to access the option windows of all installed extensions with just two clicks. A right-click on the new icon opens the Firefox add-on manager, another handy feature.

Extension Options Menu is exclusively available for Firefox 4. It can be installed directly on the project page at the Firefox extension gallery.

Christian Legnitto, the Firefox release manager, made it clear on his blog on February 1 that there will indeed be two additional betas before the development team moves to the release candidate stage. “The current plan is to build [beta 12] when the remaining betaN hardblockers are done” which “is heavily dependent on fix and blocker creation rate” said Legnitto in the blog post.

This basically means that the team did not manage to resolve all serious issues yet. The plan is to release Firefox 4 Beta 11 to the public for testing, work on the remaining issues, build Beta 12 and release it to the public as well.

Mozilla last year postponed the release of Firefox 4 to the first quarter of 2011. Developers hinted at a late February releases which may be in jeopardy because of the recent development. It may be that Mozilla has to postpone the final release of Firefox again, since the team has to work on two beta releases and at least one release candidate before the final version can be build and released. Firefox 4 Beta 11 is expected to be released in the coming days, we keep you posted as usual.

Interested users can download Firefox 4 Beta 10 from the official Mozilla Firefox 4 Beta project page. The beta is offered for Windows, Linux and Mac. It will automatically update to Beta 11 once it becomes available.

Firefox 4 Beta 10 is not the last beta. Plans are to release beta 11 before the end of this month. If plans go ahead as planned it will be the last beta release before the release candidate.

The tenth beta of Firefox 4 fixes many issues, a complete list of bugs fixed in the release is accessible here.

Notable fixes include improvements in memory usage, compatibility and stability improvements when using Adobe Flash on Mac OS X and support for a graphics driver blacklist to improve stability.

The full changelog listing those features and features that have been added in previous beta versions is available here. Downloads are provided on the same page.

Firefox users who are already working with a beta release can use the internal updating mechanism to update their browser to the latest beta version.

It pays to look at the known issues before doing so, especially if its the first time a Firefox 4 beta is installed on the system. Among the issues are problems with Hulu which blocks access to contents because of an “incompatible” browser (caused by a whitelist of user agents which has not been updated to include Firefox 4), slower scrolling in Gmail for some users and problems when downgrading to a beta release before beta 8.

“Cast a colder eye on your blockers. Some of them can wait for a dot release or Firefox 5 that I do believe will be only months after 4 comes out. We are going to a fast release cycle. It serves our users better. To do that we have to get this touch and go done with Firefox 4.

So, Firefox 5 will be ready only months after Firefox 4 has been released. The team will probably do away with x.y, e.g. Firefox 3.6, versions of the browser as they did previously.

The development team is currently fixing the remaining soft and hard blockers of the beta releases. Plans are to code freeze the development on Friday to release the next beta of Firefox 4.

Another beta may only be released if bugs are left that require beta testing. If not the team moves forward to the release candidate stage. To sum it up: If things go as planned Firefox 4 Beta 10 will be released in the next days, likely at the beginning of next week followed by the RC shortly thereafter and then a final release at the end of February.

What’s your take on the accelerated development cycle? I personally think it is more of a reaction to the Chrome development cycle and how users perceive a higher version number than anything else. We could see a Firefox 7 release at the end of this year after all which probably is not that different from Firefox 4.

That however appears to be a thing of the past, at least if the proposed patch passes quality control. Chances are however good that it will be compiled in one of the latest nightly versions of Firefox 4 Beta. Here is what Taras Glek, the developer who proposed the code change, discovered:

We page in most of xul.dll and mozjs.dll. So i figured why not try lazy-linking libxul and preloading it. Turned out lazylinking didnt make any difference, but
preloading seems to consistently shave up 2seconds of startup on my profile(40%).
I’m going to doublecheck on my favourite user’s slow computer. Here is the patch in meantime.

Basic idea is that the sequential flag + bullshit read tricks windows into reading xul in 2mb chunks instead of stupid 32k(or smaller) ones. Have to do it this way because there is no fadvise() on Windows(that I know of) A big sequential read cuts down on a lot of seeks.
[..]

I just confirmed, this also works wonders on slow harddrives. Shaved around 50% off cold startup on my reference slow system

A loading time reduction of 40-50% with a 20 line patch, that sounds efficient. But how is this achieved? From what I can gather, the developers are now pre-loading files in larger chunks which cuts down on the loading time of the browser.

It will be interesting to test this on computers with slow Firefox startup times. Information about the patch are posted on Bugzilla. (via)

Ctrl-e turned out to be less than a perfect choice as well, since it was directly adjacent to other often used shortcuts such as Ctrl-r to reload a page or Ctrl-w to close the active tab.

I recently tried to activate Panorama again in the latest Minefield nightly release only to find out that the shortcut did not work anymore. I first thought that Mozilla had decided to remove the feature again from Firefox, but the button to trigger it was still there and the feature worked as advertised. Wishful thinking aside, I had to investigate.

I did find out that the developers had change the Panorama shortcut once again. The new shortcut is Ctrl-Shift-e which is less likely to be hit accidentally by users. There is still no official option to disable the shortcut or the Panorama feature in the browser. The only valid option at this point is to block the keyboard shortcut and hide the Panorama button.

Firefox users who are using Panorama need to remember to switch to the new shortcut when the next Beta comes out. The latest official beta is still making use of Ctrl-e to trigger the feature.

Firefox 4 users will find that the browser has changed, a lot. Noticeable is that it is now a lot faster thanks to improvements on many core levels of the browser. While that is great and all it is not what users will first notice when they launch the browser after the upgrade or installation.

The Firefox interface has been changed which can cause confusion and even frustration as it is not always possible to undo those changes without third party add-ons or hacks.

What are those elements?

The Firefox header

New elements are the Firefox button at the top replacing the menu bar, tabs on top which means that tabs are now over the address bar instead of below and the Panorama icon at the top right of the bar which links to one of the new features of Firefox 4.

A right-click on a blank tab bar space opens a configuration menu with options to make changes to the interface. It is possible to move the tabs below the address bar again.

It is also possible to enable the old menu bar in the same menu. The customize option can be used to move interface elements to different locations so that the interface can look again like the one in Firefox 3, or complete custom.

Please note that the default Firefox 4 header layout is not showing a page’s title anymore in the title bar. Another change becomes obvious when hovering over links in the browser. Link destinations where shown in the status bar in Firefox 2 and 3. This has moved to the Firefox address bar in Firefox 4 which often means that the links are cut off due to space restrictions especially on low resolution monitors and if Firefox is run in a window and not maximized.

The Panorama button leads to a new page that displays tabs and groups. Firefox 4 comes with an option to create tab groups. Only one tab group can be visible at a time in each window which can be interesting for users who work on different projects at once and users who want better tab organization. Then again, it can lead to confusion if the feature is triggered accidentally (see Please Mozilla, Let Me Disable Firefox Panorama).

Firefox 4 Footer

The status bar has been removed in Firefox 4. Its replacement, the add-on bar, is disabled by default and it does not appear to be activated automatically even if add-ons make use of the space to display icons or information.

The very same menu that is used to move the tabs or enable the old menu bar can also be used to enable the new add-on bar. The add-on bar basically replaces the status bar in Firefox 4. There are however a few differences that require explanation.

The add-on bar only displays the add-on icons and information. It does not display link information nor the loading or download status. That’s all gone. The developers furthermore thought it to be a good idea to place a close button on the leftmost side of the bar. This is inconsistent for a number of reasons. First, it is the only toolbar with a close button. Every other toolbar can be enabled or disabled from the View > Toolbars menu or the right-click in the Firefox header area.

When the x is used to close, the only option to enable the add-on bar again is to use the view menu or the right-click. There is basically no reason to display the close button on that toolbar, especially since it is enabled only on user request.

The majority of changes can be reverted with add-ons or hacks. Take a look at Firefox 4, How To Undo The Changes and How To Remove The Close Button In The Firefox 4 Add-On Bar.

Firefox Add-Ons

The majority of add-ons is currently not compatible with Firefox 4. History has shown that this changes soon after the final version of the browser has been released.

While the majority of add-ons is not compatible yet by default, they can be forced to be compatible so that it is possible to install, enable and use them normally in Firefox 4.

Cautious users can look at Check Firefox Add-On Compatibility Before Upgrading to test their add-ons before they upgrade to Firefox 4. Another helpful guide is Three Methods To Force Add-On Compatibility In Firefox which explains how to force compatibility in the Internet browser.

Got additional tips or information that users need to know before switching to Firefox 4? Let us know in the comments.

It is likely that the announcement will be posted on site later today. Probably the biggest change in the latest beta is the inclusion of the IndexedDB web standard “for the storage of significant amounts of structured data in the browser and for high performance searches on this data using indexes” (via).

Interested users can download the latest Firefox 4 beta from official mirror servers that offer both http and ftp connections.

At least one additional beta will be released before the release candidate stage is reached. Firefox 4 Beta 10 Pre has already been in development for a few days and is available on the nightly servers. The beta is used to reduce the open bug count to zero.

Mozilla plans to release the final version of Firefox 4 in February 2011. (via)

We have criticized several of those changes as they do not seem to make sense or practical. Moving the link hover information to the top and other information away from the status bar have been major points.

The latest change however seems to make sense in a way. If you look at the browser interface you notice that the titlebar usually offers lots of free space. The titlebar is only used for the website title, or the Minefield button that opens the new Firefox menu.

Mozilla Links discovered information about a recent change in Firefox 4 pre testing builds that move the tabs to the very top of the screen right on the title bar when the browser window is maximized to save additional vertical space in that viewing mode.

This is an experimental feature and it is not clear yet if it will prevail. The topic is currently being discussed Bug 572160

The behavior is identical to that of the tabbar. Tabs are reduced in size when they fill out the complete titlebar and options to scroll left or right are added eventually when the minimum tab width is reached. It does feel kinda strange that the title of the active website is not displayed anymore though. It is now impossible as well to move the window even though most users are not probably going to need that feature in full window mode anyway.

Interested users can download a third party experimental build with the tabs on titlebar feature included from this website.

Even worse, if you happen to close the add-on bar accidentally you can only reopen it in the View > Toolbars menu. Lastly, the position of the close button on the far left of the toolbar is irritating to say the least and inconsistent with the position of other close buttons in the browser.

It tool me a while to find a way to remove the close button from the Firefox 4 add-on bar. You need to add three lines of code to the userChrome.css file in the Firefox profile folder.

Here is how it is done. Open your Firefox profile folder. The easiest way to locate it is to click on Help > Troubleshooting Information to reveal it. A click on Open Containing folder in the new tab opens the folder in the default file browser of the operating system.

Locate or create the folder chrome there, and in that folder the file userchrome.css. If the file does not exist create a new plain text file and rename it accordingly. Then edit it with a standard text editor and add the following lines to the file while Firefox is closed.

#addonbar-closebutton {
visibility: collapse !important;
}

Start Firefox afterwards and you should see that the close button has been removed from the toolbar.

That’s how you remove the close button from Firefox 4′s add-on bar. A discussion is currently undergoing about the close button. It appears it is there to stay, even though some users have voiced concerns.