The offsetTop calculation for elements that are contained as children of scrolled elements may be reported incorrectly in Windows Internet Explorer 8

Cumulative security update for Internet Explorer 974455 (described in Microsoft security bulletin MS09-054) introduced new logic to calculate the value of the offsetTop property. Under certain scenarios, the value of the offsetTop property may be calculated incorrectly.

When Internet Explorer 8 runs in standards mode, it may incorrectly calculate the value of the offsetTop property if the following conditions are true:

• The Web page uses the offsetTop property to determine the top position for elements.
• The elements are absolute children of scrolled elements.
• Cumulative security update for Internet Explorer 974455 is installed.

The offsetTop property is used to calculate the top position of the object in relation to the layout or coordinate parent. For more information, visit the following Microsoft MSDN Web page: For more information about MS09-054, click the following article number to view the article in the Microsoft Knowledge Base:

Cumulative security update for Internet Explorer 974455 (described in security bulletin MS09-054) was released to address identified security vulnerabilities in Internet Explorer. As part of the cumulative security update, Internet Explorer introduced additional logic to calculate the values of the offsetTop property. This additional logic did not account for certain scenarios in which the offsetTop property was requested for elements that are absolute children of scrolled elements.

To resolve this problem, install update 976749 after you install cumulative security update 974455. For more information about update 976749, click the following article number to view the article in the Microsoft Knowledge Base:
Important Do not install update 976749 if you have not installed cumulative security update 974455. If you install update 976749 without first installing cumulative security update 974455, Internet Explorer may not work correctly. If this occurs, uninstall update 976749, install cumulative security update 974455, and then reinstall update 976749.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.