Firefox 20 offers an easier way to avoid prying eyes. Image: Andy Roberts/Flickr

Mozilla turned 15 this week and the company is celebrating with a new release of its flagship Firefox web browser.

If you’re already using Firefox the latest version should arrive shortly. If you’d like to take the latest release for a spin, head on over to Mozilla’s download page.

Among the new features in Firefox 20 is a revamped per-window private browsing mode. The new private browsing mode mirrors what you’ll find in Google’s Chrome browser and is really how Firefox’s private browsing mode should have been all along.

Now when you want to start a private browsing session in Firefox you simply select the new “New Private Window” menu option. That will open a new window noting that Firefox will discard any history, search history, download history, web form history, cookies, or temporary internet files for sites you visit in that window. Any files you download and pages you bookmark will be kept.

The new per-window model is much more intuitive than the old method of private browsing which put your normal browsing session on hold, hid it away somewhere and opened a new, private session. Now it’s easy to have private windows right alongside normal windows, very handy for those who, for example, need to log in to two different Gmail accounts simultaneously.

The other major visible change in Firefox 20 is the redesigned downloads window. Mozilla proposed the new download toolbar button and overlay window design so long ago that Apple’s Safari browser has already long since copied and released its own version.

While Firefox might not be the first to get its proposed downloads interface to the web, it’s welcome nonetheless and alleviates the need to cycle through windows or hit keyboard shortcuts just to see if your downloads are done. The button also helpfully converts to a progress bar when you’re actually downloading something.

To see additional info beyond what’s available in the new overlay, just click the “show all downloads” button at the bottom of the list.

One interesting aspect of the new “Show All Downloads” window is that you may discover your history of downloaded files is larger than you think. If you’ve been clearing your download history by clicking the “Clear List” button in the old downloads window, well, that button was quite literal — it just cleared the list. It didn’t actually remove anything from your downloads history. This can be incredibly good news if you’ve misplaced a file or slightly disconcerting if you thought you were deleting references to any sensitive files you may have downloaded. To really clear your downloads be sure to use Firefox’s “Clear Recent History” menu, which has an option to actually delete everything in your download history.

It’s also worth noting that the new downloads manager works with the private browsing mode as well. You can manage downloads within private windows via a separate downloads interface which is then scrubbed when the private session is closed.

For more details on everything that’s new in the revamped download dialog, read through Firefox developer Mike Conley’s post on the new download manager.

Firefox 20 has a few goodies under the hood for web developers, including support for WebRTC‘s getUserMedia API, which allows developers to access the user’s camera and microphone (with permission) for things like Skype-style video calls. The stable release of Firefox still doesn’t offer full support for WebRTC, but future releases will continue to add more features over time.

For more details on everything that’s new in Firefox 20 — including some speed improvements for page loads and downloads — see Mozilla’s release notes.

A mockup of what it might look like to author your pages right inside Firefox. Image: Paul Rouget.

A few weeks back Mozilla’s Paul Rouget asked developers what they’d like to see in future versions of Firefox’s developer tools. The resulting thread on Hacker News is quite extensive and full of some great ideas that Rouget and others have been hacking on ever since.

The result is a bunch of new tools that are mostly still at the experimental mock-up stage, though a couple are available now in the Nightly Channel if you’d like to try them out.

The most popular request, and by far the coolest of the bunch, is the ability to do live edits in the text editor of your choice — effectively controlling Firefox with your editor. The video below shows an example of live editing via the popular Sublime Edit. This would essentially eliminate the need to jump from your editor to the browser, hit refresh, jump back to your editor, and so on. A dance that most of us are all too familiar with. Perhaps the best part, Rouget says this will work with the mobile version of Firefox as well.

Mozilla is also working on the opposite idea — authoring in the browser. That means putting an editor inside Firefox’s Dev Tools suite. Thus far this idea is less fleshed out, but the possibilities include putting in something like jsFiddle or perhaps a more traditional file-based editor.

Other new tools include some catch up features that bring Firefox’s Dev tools up to speed with what you’ll find in WebKit browsers. Examples include a new network panel prototype and the ability to doc the tools to the right side of the screen — great for wide monitors (this is already available in Nightly). There’s also a new “repaint” view that shows what gets repainted on the page, very useful if you’re trying to improve performance. Rouget has also been working on a new, dark theme for the Firefox dev tools.

Rouget recently added a font inspector panel (available in the Nightly Builds) that makes it easy to see which fonts a page is using, including details like whether or not the font file is local or served through a service like Typekit, as well as the actual @font-face code used.

In what appears to be an unrelated effort, Mozilla developer Dave Townsend has been hacking on Firefox’s Tilt View Tool. Tilt View offers a 3D look at a page that can be very helpful for visualizing the structure of your code and spotting bugs you might otherwise miss. Townsend has come up with a number of ways to extend Tilt, including showing only links and only elements that change on hover.

Townsend even suggests that in the future you might be able to pair Tilt with your site analytics to see which links are most frequently clicked. Unfortunately you’ll have to wait a while before these features are actually available in Firefox; Townsend’s hacks rely on some core Firefox features that aren’t ready for prime time just yet.

While many of these coming features are, as yet, only prototypes, things are clearly looking up for Firefox’s dev tools. For more details on everything that’s new, be sure to check out Rouget’s post, as well as the related Hacker News thread that Rouget has been posting to with some follow up info.

So, so round. Image: Screenshot/Webmonkey.

Firefox’s tabs will soon sport a sleeker, rounded design.

The new design will likely arrive in the Nightly Channel in the next few days, but if you’d like to test it today, you can download the Firefox UX branch. Retina MacBook Pro users should note that, thus far, the new curvy tabs don’t support high-DPI screens.

The new curved tabs look like slightly over-sized, more rounded versions of the tabs Google Chrome has always used. Unlike Chrome, tabs in the background are nearly invisible.

The big question is why? Mozilla’s answer seems to be little more than “because we can”. On the plus side, the re-skinned tabs will bring a bit of a speed improvement thanks to new graphic elements and faster “paint” times.

For more details on the speed improvements see Firefox developer Mike Conley’s write up on the new curvy tabs.

Firefox’s new per-window private browsing mode. Image: Screenshot/Webmonkey.

Firefox 20, currently six weeks away from a stable release, brings two nice new features to the popular open source browser — per-window private browsing and a new downloads manager.

If you don’t want to wait six weeks for the final version of Firefox 20, head on over to the Beta Channel download page and grab a pre-release copy today.

The per-window private browsing mode mirrors what you’ll find in Google’s Chrome browser and is, frankly, how it should have been all along. When you want to start a private browsing session in Firefox 20 you simply select the new “New Private Window” menu option. That will open a new window noting that Firefox will discard any history, search history, download history, web form history, cookies, or temporary internet files for sites you visit in that window. Obviously files you download and pages you bookmark will remain.

The new per-window model is much more intuitive than the old method of private browsing which put your normal browsing session on hold, hid it away somewhere and opened a new, private session. Now it’s easy to have private windows right alongside normal windows, very handy for those who, for example, need to log in to two different Gmail accounts simultaneously.

The change does have some potential consequences for Firefox add-ons using the new(ish) SDK. If you’re an add-on developer, head over to the Mozilla Add-ons blog for more details.

The other big change coming in Firefox 20 is the revamped downloads window. Mozilla proposed this download toolbar button and overlay window design so long ago that Apple’s Safari has already long since copied and released its own version.

The new downloads overlay. Image: Screenshot/Webmonkey.

While Firefox might not be the first to get its new downloads interface to the web, it’s welcome nonetheless and alleviates the need to cycle through windows or hit keyboard shortcuts just to see if your downloads are done. If you want more info than is shown in the new overlay (which comes up when you click the toolbar button), the old, separate-window style downloads panel is still available.

For more details on everything that’s new in Firefox 20, be sure to check out Mozilla’s beta release notes.