The road to 1.5

"Deer Park", the codename of the Firefox 1.1 and 1.6 Alphas, did not include Firefox branding.
"Deer Park", the codename of the Firefox 1.1 and 1.6 Alphas, did not include Firefox branding.

On June 23, 2005, the Mozilla Foundation announced that Firefox 1.1 (which became Firefox 1.5) and other new Mozilla products will no longer support Mac OS X v10.1. This is intended to improve the quality of Firefox releases on Mac OS X v10.2 and above. Users of 10.1 may still use Firefox versions from the 1.0.x branch (e.g. Firefox 1.0.7).
Updated options window introduced in Firefox 1.5
Updated options window introduced in Firefox 1.5

Firefox 1.5 was released on November 30, 2005. The original plan was for a Firefox 1.1 and later a Firefox 1.5. After the first two 1.1 alpha builds, the Mozilla Foundation abandoned the 1.1 release plan and merged it with the planned feature set of 1.5 instead, with 1.5 being released later than was planned for 1.1. The new version resynchronised the code-base of the release builds (as opposed to nightly builds) with the core "trunk" which contains additional features not available in 1.0, as it branched from the trunk around the 0.9 release. As such, there has been a backlog of bug fixes between 0.9 and the release of 1.0, which are now available in 1.5. Version 1.5 implements a new Mac-like options interface, which has been the subject of much criticism from Windows and Linux users, with a "Sanitize" action to allow a person to clear their privacy related information without manually clicking the "Clear All" button. A user can clear all privacy-related settings simply by exiting the browser or using a keyboard shortcut, depending on their settings. Moreover, the software update system has been improved (with binary patches now possible). There are also improvements in the extension management system, with a number of new developer features.

Also, Firefox 1.5 has (partial) SVG 1.1 support, as shown in Mozilla's Bugzilla database. This unplanned movement may be due to the release of Opera 8.0 on April 19, 2005, which supports SVG Tiny.

Alpha builds of Firefox 1.5 (1.1a1 and 1.1a2) did not contain Firefox branding. They were labeled "Deer Park" (which was Firefox 1.5's internal codename) and contained a different program icon (see installation screenshot, right). This was done to dissuade end-users from downloading preview versions, which are intended for developers only.