Mozilla announced that it has stopped making changes to the first release candidate of Firefox 3.0 and is working to get that build to users by the end of the month.

"We are code complete for Firefox 3 Release Candidate 1 (RC1)," said Mike Schroepfer, Mozilla's vice president of engineering, in a post to the company's development blog on Saturday. "If all goes well we should have the Release Candidate publicly available in late May."

The release candidate -- typically the final stage before software goes final -- will be pushed to more than 1.2 million users when it launches, Schroepfer said.

It's possible that RC1 will be the one and only release candidate. "The QA cycle for RC1 is more extensive than the betas since this may be our last milestone," Schroepfer said in a message posted to the "mozilla.dev.planning" message forum. However, if serious bugs are uncovered, "we will continue to release new Release Candidates until we are ready for final ship," he said.

Mozilla developers quashed several bugs starting Friday morning to make the Saturday "code freeze" deadline, according to the mozilla.dev.planning forum. Among the fixed flaws was a regression bug that made Firefox 3.0 incorrectly convert characters when loading URLs.

Mozilla issued three release candidates in the run-up to the final code of Firefox 2.0 in 2006; as recently as late March Schroepfer said that he expected Firefox 3.0 to follow that same pattern.

The open-source developer last updated its under-construction Firefox 3.0 nearly six weeks ago when it released Beta 5 to testers. Days before that, Schroepfer said Mozilla was shooting for an early-May RC1, but warned that that target might slip. "The release candidates will move a little slower than beta," he said in late March, because of the need to account for more public feedback than with earlier builds.

Also in late March, Schroepfer said that the final version of Firefox would likely ship in June. Monday, he said that Mozilla is still on track for a final release by the end of next month.

Firefox currently accounts for about 17.7 per cent of the browser market, according to Net Applications' most recent data. Microsoft's Internet Explorer retains the browser lead with 74.8 per cent, while Apple's Safari holds down third place with 5.8 per cent.