 Beta versions of Opera 9 included an Easter egg that, when triggered, affects the Acid2 test.After the page has been open for a while, the eyes of the smiley will follow the cursor around and when the user clicks on the eyes, a JavaScript alert will read "Because just passing is not enough ;)".The changes to the Acid2 code were applied using Opera's browser.js feature, and remain available in a separate User JavaScript file.