The type or namespace name 'Window' does not exist in the namespace 'System.Windows'

Question

I am trying to write an extension method for the WPF Window class. I am doing it in a class library project in my solution, so that I can use it in all my projects in the solution.

Here is my code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;

namespace ExtensionMethods
{
    public static class MyExtensions
    {
        public static void ResizeToPrimaryScreenWorkingArea(this System.Windows.Window w)
        { 
        }
    }
}

When I try to compile this, I get the following error:

The type or namespace name 'Window' does not exist in the namespace 'System.Windows'

Yes, I DID add references to System.Windows and System.Windows.Forms in my class library project, and they are showing under References in the project in Solution Explorer.

What am I doing wrong?

Solution

Add PresentationFramework.dll reference to your project it contains the System.Windows namespace.

http://msdn.microsoft.com/es-es/library/system.windows.window(v=vs.110).aspx

Comments

[Tom Blodget]

@JoeMjr2 You need to understand that there is no required relationship between the name of an assembly and the namespaces of any types it defines. Nor any requirement that all types in a namespace be defined in a single assembly. The documentation link in the answer specifies the assembly for the class you are trying to use.

[JoeMjr2]

Tom, excellent point! I'd never thought about it that way. In most cases the assembly names and namespaces jive, but I guess not always. I'll be sure to check that line in the docs from now on!