Just when I am about to have a rest after I happily cleared the "secure and nonsecure" warning in IE7. Today, I test my web application in IE6. I got the "secure and nonsecure" warning again.
Here come the nightmare again, having to test your application in X different browsers on Y different Operating Systems. You fumble to fix bugs for one specific platform and seeing your fixes screwed up totally in another platform.
Fortunately, this time, "I'm Feeling Lucky". I tried keyword "yui secure nonsecure" in google, and found an answer on the first page 3rd item, titled: "Bug in iframe shim code in 0.12.0 container.js?". It is only a one line change in container.js. But, I know it could take me a couple of days to narrow down to it. Thanks to Arun, it only took me 10 minutes to fix the problem this time.