The Mozilla Foundation has released a test preview of the next version of the Firefox browser, showing off the upcoming release's improved pop-up blocking, enhanced navigation and added support for Web standards.

Mozilla Firefox 1.5 Release Candidate 1 is available now so testers can make any last-minute fixes before the final code is released. The foundation also warned on its site that the release is for testing purposes only without end-user support, so users who do not wish to download it for that purpose should use the current version 1.0 of the browser.

Firefox 1.5 should be available in full release before the end of the year, with one more preview to be made available as early as 11 November if feedback from Release Candidate 1 is positive, according to the Mozilla.

New features in the browser include a better system for updating software, faster navigation using the "Back" and "Forward" tabs, and a redesigned Options/Preferences window that increases the number of category icons and moves them from the left side of the window to the top.

Firefox 1.5 also includes new support for Web standards, adding support for Scalable Vector Graphics (SVG), JavaScript 1.6 and CSS. It also adds improved DHTML accessibility features and better support for Mac OS X.