March 24, 2009
IE8 et compatible, vous
There are a million new features that I won't cover here, but along with much welcomed CSS 2.1 standards support and enhanced security come compatibility issues. If you've been paying attention, chances are your sites already employ
X-UA-Compatible meta tags that instruct IE8 to render either in standards mode, or to act like previous versions of the IE renderer. You may even have found that your site works fine in IE8 w/o these tags.
You're probably going to want to add them anyway. Here's why: While IE8 defaults to standards mode, at install time users are offered the opportunity to use the Compatibility View List, a sort of black list of sites that have been reported to render poorly. For users who have opted-in, sites on the list are automatically rendered in compatibility mode. Some examples off the top of the list include Amazon, the BBC, and Craig's List.
While IE8 in compatibility mode mostly matches IE7's standards mode, there are some differences; to ensure your site renders as you intend, it's probably best, at least for the time being, to declare for yourself which render mode to use if for no other reason than to limit the number of platforms and configurations you must test.
For further reading:
The MSDN tech article META Tags and Locking in Future Compatibility.