Mozilla is thinking about dropping Firefox support for Apple's Mac OS 10.3, the three-and-a-half-year-old operating system also known as Panther.

In a thread on the mozilla.dev.planning forum and a proposal posted to Google Docs, Mozilla developers argued whether Firefox 3.0 should run under Panther.

"I'd like to propose that we drop support for Mac OS X 10.3 (Panther) on the Mozilla trunk," said Josh Aas, Mozilla's resident Mac OS X developer. "I believe doing so will result in a significantly higher quality release of Gecko 1.9 [Firefox 3.0] for the vast majority of users on Mac OS X."

Aas cited finite development and testing resources, as well as the upcoming release of Mac OS 10.5, a.k.a. "Leopard," this October as reasons for backing away from Panther. "Dropping support for Panther would also free up engineering resources," he said. "We are already running short on time to deliver a product that works well on Tiger and Leopard.

"There is already a backlog of tricky Panther-only regressions, bugs and performance issues in areas ranging from widgets to fonts and gfx/Cairo that I suspect will consume at least a few weeks of development time," said Aas.

Others on the thread, however, urged caution. "I'm sympathetic to the economic argument, especially given our scarce Mac hacking resources, but I think we need to be more deliberate about it," said Mike Shaver, Mozilla's technology strategist.

Still others took issue with the whole idea of abandoning the older operating system. "I want to have a kick-ass Firefox 3 that makes Safari quake in its boots, but I also don't want to dismiss the loyal Firefox users that still may be using 10.3," said Marcia Knous, another Mozilla developer.

Mozilla isn't afraid of dropping support for older operating systems. On the Windows side, the company has already announced that Firefox 3.0 will not support Windows 98 and Windows Millennium, both of which were dropped from Microsoft's own support list last summer. And last week, a Mozilla executive said the new browser, expected to ship before the end of the year, probably won't support older distributions of Linux.

Apple typically offers security updates to just two editions of Mac OS X simultaneously; after it launched Mac OS X 10.4 in April 2005, it stopped posting updates for Mac OS X 10.2, alias Jaguar. If that trend hold true, Apple will cease security patches for Panther when it launches Leopard.