One of the best features of IE 9 on Windows 7 is its ability to display an overlay icon on the pinned-site taskbar button. Why is the display overlay icon so important? Because a pinned site may be sitting idle, hidden by other sites or applications. The overlay icon gives you a way to display dynamic content or updates of things that are going on behind the scenes that may catch users' attention and drive them to action.
You could display a small bell indicating an event or appointment, or an envelope icon to let the user know that a new message has arrived. The overlay icon appears in the lower-right corner of the pinned-site task bar button. The overlay icons are not visible if the site is not opened, however, or if the site is not actually pinned to the task bar.
The following code sample adds overlay1.ico on top of the associated task bar button for the pinned site, and includes a hover-over tool tip identifying the overlay icon with the string 'Overlay 1':
window.external.msSiteModeSetIconOverlay('http://host/images/overlay1.ico', 'Overlay 1');
To clear the overlay icon, use the following code:
This series of examples is just a drop in the bucket. Check out Microsoft's Internet Explorer 9 Guide for Developers for comprehensive coverage of the unique features of IE 9 and explanations of how to customize your Website to take advantage of them.
Bear in mind, though, that IE 9 is compatible only with Windows 7 and Windows Vista, meaning that your IE 9 customizations will be worthless for two out of three PCs. Keep things in perspective, and don't go overboard investing time and effort to cater to this one browser.
Because businesses are slow to upgrade, consumers are leading the charge toward adopting Windows 7 and Internet Explorer 9. Consequently, these changes will have a direct impact with how the general public interacts with your site.
If your site targets average consumers, you should explore and take advantage of the unique features of IE 9. You don't have to be an expert programmer, and you don't have to redesign your entire Website to give your visitors a reason to pin your site to their task bar--and from there to deliver a more immersive, application-like experience.