The blend-2012 tag is for Blend for Visual Studio 2012 related issues.
Blend for Visual Studio 2012 helps you design and build user interfaces by providing you with an accurate design surface and tools that let you visually create and edit Windows Store applications. These new design tools take advantage of Windows 8 technologies to create dynamic applications that run on a wide variety of Windows-based hardware. You can choose to design your user interface using HTML or XAML.