Mozilla stopped supporting Mac OS X 10.4, aka Tiger, in September 2009, but left a large amount of Tiger bits in the development code.
Now, said Josh Aas, a platform engineer for Mozilla who works on Mac OS X integration, it's time to either restore support for the five-year-old operating system or remove the code from the development tree.
"We would like to take advantage of more modern technologies on Mac OS X and 10.4 support has been a hindrance," said Aas in a message yesterday on the mozilla.dev.planning forum.
According to Mozilla's metrics, 24 percent of those running the Mac version of Firefox 3.5 rely on Tiger, while 12 percent of those running the just-released Firefox 3.6 do.
Half of all users run Firefox 3.5 on Mac OS X 10.5, aka Leopard, while 59 percent run Firefox 3.6 on OS X 10.6, or Snow Leopard .
Aas noted that Tiger users can continue to run Firefox 3.6, which supports the older operating system, until that version is retired from support.
Currently, that end-of-support would come sometime in 2011, as Mozilla doesn't expect to deliver a major update to its open-source browser until late this year at the earliest.
Mozilla's policy is to support an edition for approximately six months after a new version ships.
"We are often one of the last vendors to continue supporting older Mac OS X releases," said Aas.
There was only one dissenting voice on the forum, but he took Mozilla to task for ditching him.
"As it stands now, it [is] impractical for me [to] update either machine due to lack of funds," Phillip Jones said, referring to a pair of PowerPC-based Macs running Tiger.
"Most just take what they are given and stew in the background. Silly me I don't. So in the end my opinion doesn't count for anything."
For its part, Apple has already retired Tiger from security update support. The last time it patched vulnerabilities in Mac OS X 10.4 was September 2009
Firefox 3.6, which runs in Tiger, can be downloaded from Mozilla's site. According to Mozilla, nearly 39 million copies of the new edition have been downloaded since its January 21 launch.
As of January 25, about 6 million Mac users were running Firefox 3.5 or Firefox 3.6.