Differences between IE8 Compatibility View and IE7

Microsoft or IE8 Teams need feedback from you or community if finding broken site.
at this time.some differences has found between IE7 and IE8.

Cross Document Communication
Hacks enabling cross-domain, cross-document communication have been disabled for security reasons.

SOLUTION: Use Cross Document Messaging (XDM) to work around this change.



Extending the Event Object
IE exposes new properties for certain AJAX features such as Cross Document Messaging (XDM), even in Compatibility View. Adding custom properties to the Event object can conflict with these new properties, such as "source".
event.source = myObject; // Read-only in IE8

SOLUTION: Change the names of conflicting custom properties to avoid collision.
event.mySource = myObject


Attribute Ordering
The ordering of attributes has changed, affecting the attributes collection as well as the values of innerHTML and outerHTML. Pages depending on a specific attribute ordering may break.
attr = elm.attributes[1]; // May differ in IE8

SOLUTION: Reference attributes by name as opposed to their position within the attributes collection.
attr = elm.attributes["id"];


Setting Unsupported CSS Values
Assigning CSS values that were unsupported in IE7 but are supported in IE8 Standards Mode will not generate exceptions in IE8 Compatibility View. Some sites use these exceptions to determine if a particular value for a CSS property is supported or not.
try {
elm.style.display = "table-cell";
} catch(e) {
// This executes in IE7,
// but not IE8, regardless of mode
}

SOLUTION: Short of version detection, this is a difficult issue to work around. If this behavior is essential to a page, updating the page to run in IE8 Standards Mode may be the best approach.