Mozilla is considering just two more security updates for Firefox 2.0 before it retires the browser at the end of this year.

"We're starting to consult the [development] community for feedback," said Mike Beltzner, the director of Firefox, prior to setting a final 'end-of-life' date. If all goes according to plan, the last update for the older browser will be Firefox 2.0.0.19. The current build of Firefox 2.0 is 2.0.0.17, which was released last month to patch 14 vulnerabilities.

Mozilla's policy is to support a browser for six months after it's been superseded by a new version. The company unveiled Firefox 3.0 in mid-June; shortly after that, Mozilla announced that it would stop patching Firefox 2.0 later in the year.

Beltzner confirmed Wednesday that Firefox 2.0 remains on track for retirement by the end of December.

He also noted that a majority of Firefox 2.0 users have taken advantage of an upgrade offer to Firefox 3.0 that Mozilla triggered two months ago. "Presently two-thirds of our users are using Firefox 3, with more than 50% accepting the first major upgrade offer back in late August," said Beltzner in message posted early Wednesday to the Mozilla site.

One user on the mozilla.dev.planning message forum asked Beltzner how the end-of-life for Firefox would affect Thunderbird 2.0, the e-mail client that's built on the same Gecko foundation as Firefox 2.0, or other applications, such as SeaMonkey or Camino, also based on Gecko 1.8.1. "Based on the current [Thunderbird 3] release planning, [Thunderbird 3] will be released 3-4 months after the Gecko 1.8 [end-of-life], when [Thunderbird 2] is still the stable release," said Simon Paquet.

Thunderbird, which is developed and maintained by Mozilla Messaging, a Mozilla spin-off, is considerably behind Firefox in its shift toward version 3.0, which is based on the Gecko 1.9 tree. Earlier this month, for example, Mozilla Messaging renamed what had originally been Beta 1 of Thunderbird 3.0 as, in fact, a third alpha. Previously, Mozilla Messaging had said the first release candidate for Thunderbird 3.0 would likely ship in late January, with a final some time after that.

Currently, the Thunderbird timetable omits any dates after Nov. 18, when Beta 1 is to enter "code freeze" status.

But the demise of Firefox 2.0 support doesn't mean that Thunderbird 2.0 users will be left out to dry, Beltzner said today, making an effort to differentiate work on Firefox from the underlying Gecko engine. "The end of support for Firefox 2.0 doesn't mean that [developers] won't be able to work on the Gecko code," he said. "It just means that our focus won't be on actively maintaining that [1.8] branch [of Gecko]."

Other Mozilla developers had responded previously to Paquet's concern about a lack of patches for Thunderbird, noting that during earlier end-of-life moves, programmers continued to support the e-mail client.

"Mozilla, in some form, will provide support for Thunderbird based on the official lifecycle policy, like we did for 1.0 and 1.5," said Michael Conner, of Mozilla, in a message posted in late September.

"Even after we did the end-of-life for Firefox 1.5 [in May 2007], developers who were employed by Mozilla, and members of the Gecko community would respond to patch request from the Thunderbird team," added Beltzner.