Opera Software on Monday released a final version of Opera 15, the first of its desktop browsers to rely on the open-source Chromium engine.
A company employee also announced that security updates for the older Opera 12 will end with the next bug-fix release, putting pressure on users to upgrade.
Google's Chrome and Apple's Safari have long used WebKit as their foundations, but Google is dumping WebKit for its own variant, called "Blink," to power Chromium. Opera has promised to follow in Google's footsteps; the shift to WebKit is a first step in that direction. The new browser, in fact, does identify itself as built atop WebKit.
Opera 15, which hit beta in late May, was released in final form today for both Windows and OS X. A Linux version will debut "in the near future," according to Opera.
But the appearance of Opera 15 has implications for users of older editions of the Norwegian browser, the company acknowledged.
In a blog post, Mark Wilton-Jones, who works in Opera's QA (quality assurance) group, said, "With this release, we will be starting afresh with our monitoring and fixing of security issues."
That means security updates for older editions of Opera will soon end, said Wilton-Jones. "Opera 12.16 is the last planned security update for Presto based Opera for Desktop. Users are urged to update to Opera 15 ... at the earliest opportunity," he wrote.
Opera 12.16 has not yet been issued, but it is the next version up for the v. 12 line, which is currently at v. 12.15.
But as at least one commenter on Wilson-Jones' blog pointed out, there's confusion about whether v. 12.16 will be the final security update.
In a separate blog today, Opera's Sebastian Baberowski, who works on the company's desktop browser team, implied that v. 12 will be maintained for much longer.
"We have neither asked nor forced our 12.x users to upgrade to Opera 15," Baberowski wrote. "You can expect that we will keep Opera 12.x up to date and secure. In the future, once we are comfortable with the feature set, we may ask you to upgrade [to Opera 15]."
Opera did not reply to a request to clarify the apparent contradiction between Wilton-Jones' and Baberowski's comments.
Many users among the over 300 who left comments on Baberowski's blog post today were very unhappy about the debut of Opera 15 and the looming end-of-life for Opera 12, criticizing the former for missing features and slamming the company for abandoning years of work on the in-house browser engine.
"If [Opera] 15 remains the way it looks now, then it'll be rather like what happened to Flickr in May -- ugly and unpleasant to use, and carrying the implicit message that what users like and need doesn't matter," wrote someone identified as "0paulh177."
While Opera has a devoted following among its users, it has never climbed out of the Web battle basement: Opera was used by just 1.6% of those who accessed the Internet last month.
Opera 15 for Windows and OS X can be downloaded from the company's site.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed . His email address is email@example.com.