Opera publishes 10.5 pre-alpha for Labs

Opera urged users to back up their systems before downloading the new software

Browser developer Opera Software has officially made available its Opera 10.5 pre-alpha for Labs. The software is currently available only for Windows and Macs, but a Unix/Linux version is said to be coming later.

Roberto Mateu, a product analyst at Opera, said in a blog post that, while the company does not usually open software to user testing this early in development, the company is "really excited" by the product and is interested in user feedback.

Mateu also explained that the software uses a new JavaScript engine called Carakan which is seven times faster than the previous SunSpider system used in Opera 10.10. It also has a 2.5 version of the Presto rendering engine.

The official launch comes two days after the software was leaked as an internal build and made available to download.

Responding to the leak on a seperate blog posting Opera desktop team manager Huib Kleinhout urged users to resist downloading the leaked version, citing security concerns.

"There are some reports about an old internal build of 10.5 being available. Don't run it. The official build on Tuesday is much better and you don't risk getting nasty Trojans on your PC," he said.

The company made no mention of the leak on today's blog posting, but Mateu did stress that even the official version of 10.5 Pre Alpha was an "unstable development build" and urged users to back up their systems before use.