Mozilla has released the second alpha release of Firefox 3.0, with the new Gran Paradiso build of the internet browser now available for web application developers to download.

At this stage of development, Gran Paradiso isn’t ready for general consumption. Its developers have released it as “an early developer milestone” to show progress that’s being made on the next generation of Mozilla’s layout engine, Gecko 1.9.

Mozilla said that Gecko 1.9 does not support Windows 95, Windows 98, and Windows ME, and advises that the release is to be used for “testing purposes only”, and is aimed specifically at application developers and its testing community.

“Current users of Mozilla Firefox should not use Gran Paradiso Alpha 2. There are no significant user interface changes in Gran Paradiso Alpha 2, however there are many core layout and rendering improvements,” said the developers.

Among changes in the Gran Paradiso Alpha 2 release is the removal of Mac OS X v10.2 as a minimum system requirement; Mac OS X v10.3.9 is now the minimum requirement. The code that handles calculation of widths and absolutely positioned elements, as well as the code for handling incremental layout of pages, has changed. “Greatly improved Mac widgets support” is also listed as an improvement. Other changes have been made as well - a complete list is available online.

The first version of Firefox 3.0 was released to developers in December.