Mozilla hopes to deliver the second beta version of Firefox 4 to users before the end of next week, according to the minutes from its recent developer’s meeting.

Tuesday’s meeting notes show the team has picked next Thursday, July 22 as the proposed ship date for Firefox 4 beta 2.

There are several enhancements on the way in beta 2, but the one sure to raise the most interest (or the biggest stink) is the new tabs-on-top interface for Mac OS X users. Windows users got the tabs-on-top look as the default interface in Beta 1 earlier this month. With beta 2, the rollout continues to other OSes.

The tabs-on-top interface is a growing trend among browser vendors. It was popularized by Google Chrome, which shipped with top-tabs as the default within its initial release. Reaction was mostly positive — Opera now puts the tabs on top, and Safari tried the same thing in a beta release thing before abandoning it. But there are some within the Firefox user community who don’t want to see Mozilla’s browser make the switch just to chase the latest design fad.

Mozilla’s lead user experience designer Alex Faaborg defends the decision, saying it has nothing to do with fashion. By putting the tabs on top, he argues, Firefox 4 will be better suited to running web applications that sit in their own tab. It turns the tab bar into something much closer to a dock or a task bar — a fitting change, since the browser is becoming something much closer to a GUI for an operating system.

Here’s a mock-up showing several web apps running in top-placed tabs in Firefox. The browser may not end up with this design, but it nicely illustrates Faaborg’s idea.

Here’s a seven-minute video his team produced that furthers the debate:

Of course, if you don’t like your tabs up top, you can always revert to the old look in the browser’s View menu.

Some other stuff due in Firefox 4 Beta 2: CSS transitions, better handling of retained layers on pages and a new feature in the add-ons manager that confirms when an add-on has been installed.

As always, Mozilla’s ship dates and feature lists (especially for beta releases) aren’t final. The team usually sticks to the proposed plan, but don’t be angry or surprised if the release slips to the following Monday.

The final browser is expected within a few months, and you can read our preview of Firefox 4 on Webmonkey.

Illustration at the top courtesy of Mozilla. Firefox mock-up by Stephen Horlander and Alex Faaborg/Mozilla/CC.

See Also:

• Mozilla Moves Tabs to the Top for Firefox 4
• Firefox 4 Beta 1 Now Available for Download
• Firefox Sync Graduates From Labs, Ready for Firefox 4
• First Look: Firefox 4 Preview Delivers Speed, Revamped Interface