Mozilla Corp.'s lead engineer isn't worried about Microsoft's upcoming Internet Explorer 7, but instead is focusing on getting the next version of Firefox out the door.

"IE 7 is a pretty good catch-up," said Mike Schroepfer, Mozilla's vice president of engineering. "But it does some funny things with tabs and the UI that I don't understand why they did it."

Mozilla, which plans to ship the next major update, Firefox 2.0, by early in the third quarter, is concentrating on adding features and improvements to make sure that its browser stays ahead of Microsoft. "Firefox 1.5 was focused on the platform, but 2.0 will be about the UI, a smaller set of platform things, and more features that the user will see," Schroepfer said.

Development of Firefox 2.0 has been stalled as of late. "Open-source development leverages so many different people that it's ultimately less predictable because of that, and because you're dealing with volunteers," admitted Schroepfer. "Essentially, we trade predictability for quality and the total amount of work we can do on a project," he said, compared to commercial, proprietary development.

The Firefox 2.0 first alpha was to release Feb. 10, but now, said Schroepfer, "is a couple of weeks out."

Firefox 2.0's development roadmap lists the main feature updates and additions, and their priorities. Among those at the top are redesigns of the browser's bookmark and history system, security enhancements to extensions, the popular plug-ins, search engine improvements, and changes to the tab-based user interface.

"We're still testing 'Places,'" said Schroepfer, referring to the 2.0 feature that will combine bookmarks and browsing history. "You'll be able to very quickly search through History and bookmarks, and we're moving a bit more toward a tagging metaphor, where a bookmark can exist in multiple folders."