Mozilla has released the second alpha of Shiretoko, the development codename of Firefox 3.1. Alpha 2 brings a handful of improvements and new features that help advance the web to a more open, standards based stage, while tweaking the user experience.

The main improvement is the support for <audio> and <video> tags with native Ogg Theora and Vorbis video and audio codecs, as announced a few weeks ago. The addition of this feature will enable web and content developers to publish their audio and video creations in a royalty free format and don’t depend on the availability of a certain plugin in a specific platform (like Flash or Silverlight do).

The new Ctrl+Tab behavior which shows a preview of the three (customizable number) most recently used tabs, has been extended with options to close the tab (hold Ctrl and press W) while switching and select the desired tab by clicking on it. The favicon is still scaled up but at least it’s not skewed any more.

True drag and drop tabs across windows is also available. In Firefox 3 you are able to drag tabs across windows but it just triggers a reload of the same web page. Now tabs are just reparented to a new window programmatically.

To help a more consistent interface, a new search widget is now available in the bookmarks and history sidebar, the get add-ons search, download manager, password manager, and anywhere a search is needed. For inline search, the magnifier turns into a cancel icon, otherwise, it stays the same.

Web developers are being treated to a few very important improvements. Most noticeable, support for querySelectors and querySelectorsAll interfaces as defined by the WWW Council draft, which allow faster (up to 7X in some cases), easier access to specific web page elements based on a variety of criteria.

Support for ::before and ::after CSS 2.1 selectors along with  -moz-border-image (no final spec yet, hence the vendor prefix), word-wrap: break-word, text-shadow, box-shadow and column-rule CSS3 properties, are all in and available for use.

Gmail is shipped as a web content handler for mailto: links. The handler uses a secure connection unlike the one posted here a few months before. You may want to check it back and update the handler.

Since mailto: links can be handled by a web service, the context menu lets you open these in a new tab.

Since Alpha 1, Shireotoko supports media queries, an extension to CSS2 media selectors that allow web developers to provide page styling appropriate for the device in use. In addition to declaring a medium, developers will be able to query for color capabilities, screen aspect, resolution, and size, etc.

Regarding the Acid 3 test, Firefox got to pass another test to score 85/100. There are about five bugs related to Acid 3 tests already in the works that if solved would push it to at least 90/100 in the next development releases.

An option has been added to the Help menu to report a web page identified as a malware serving site as a false positive, but I don’t think it is discoverable enough.

TraceMonkey, the JavaScript optimization module that brings outstanding performance improvements to most web applications is disabled by default in this release because of some nasty bugs, but this should change soon.

Also coming in future releases, most likely Beta 1, is geolocation support which was added some days ago, and will enable web developers to provide content customized to a user specific location.

Private browsing (now available in Safari, Chrome and Internet Explorer Beta 2) has been dropped, while  tag autocomplete and bulk tagging are now at risk. On the other hand, performance improvements to Places to reduce disk access is on track.

Further reading: Firefox 3.1 Alpha2 release notes