Consider the following scenario:
You have an application that runs on a Windows RT 8.1, Windows 8.1, or Windows Server 2012 R2-based computer.
The application uses an extensible application markup language (XAML) control that is vertical-scrollable, read-only, and multiline, such as TextBox or RichEditBox.
You run the application, you use the scroll wheel on the mouse to scroll the content, and then you try to select items in the control.
In this scenario, the scroll bar jumps back to a random location. Therefore, you cannot select the intended items.
To resolve this issue, install update 2919355. For more information about how to obtain this update rollup package, click the following article number to view the article in the Microsoft Knowledge Base:
2919355 Windows RT 8.1, Windows 8.1, and Windows Server 2012 R2 Update April, 2014
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684 Description of the standard terminology that is used to describe Microsoft software updates