Solution: Wide live tile not available even it is defined in XML template

The problem is that default Windows Store project generated by Visual Studio 2012 does not contain wide logo bitmap.

So:

1. Create a wide logo in any image editor. Size must be 310 x 150 pixels.
2. Save it as PNG format, e.g. WideLogo.png.
3. Move it to Assets subdirectory of your project directory.
4. In Visual Studio, double-click on Package.appxmanifest file.
5. On the first tab, write Assets\WideLogo.png into the Wide logo edit box.

Solution: 'XmlDocument' could not be found in Windows Store application code

When I added XmlDocument class to the code of my Windows Store (Windows 8 RT) application, I got the following error:

The type or namespace name 'XmlDocument' could not be found (are you missing a using directive or an assembly reference?)

Adding using System.Xml; directive did not help...

Solution: add using Windows.Data.Xml.Dom; directive:

using Windows.Data.Xml.Dom;
...
var xmlDocument = new XmlDocument();