Firefox 1.5b1 is now out and from my first test runs with script.aculo.us (functional/unit tests), and an effects-heavy AJAX applicationeverything seems to work fine. FF 1.5b1 Download is here: http://www.mozilla.org/products/firefox/all-beta If you have the chance, please test Firefox 1.5b1 against real-world sites using Prototype and/or script.aculo.us so we can find out if there are any issues. Thx, Thomas