In August 2005, Google launched an instant messenger: Google Talk. It was similar to Yahoo! Messenger or AOL Instant Messenger in that you had to download and install a little program to be able to send and receive instant messages. A few weeks ago, Google Talk was integrated with Gmail, so Gmail users can send instant messages to each other directly from the Gmail web-based interface.
While web-based chat solutions have been available for a long time, by integrating Google Talk into Gmail, it instantly became the most widely used web-based instant messenger. Getting a web-based instant messenger to work smoothly for such a large number of users is no small feat.
However, this method has a significant downside: while the document is loading in the iframe, on IE the logo on the top right of the window keeps spinning. This gives a wrong impression to the user. The clever people at Google found a solution to this IE-specific problem: instead of using an invisible iframe directly in the page, they create an instance of the "htmlfile" ActiveX object, and create the iframe in that object. Alex Russell discovered this clever hack in the Gmail code, and I totally agree with him on this:
From long and painful experience and amazingly deep respect, I take my hat off and bow to whoever it was on the GMail/GTalk team that figured this out. It’s a hell of a hack. It’s no wonder that Google has been able to attract and develop the best DHTML hackers in the world.