To transform a classical library project to a WPF library project

To transform a classical library project to a WPF library project (in order to add UserControls, Windows, ResourcesDictionaries, etc.) you can add the following XML in the .csproj file in the first PropertyGroup Node :

<ProjectTypeGuids>{60dc8134-eba5-43b8-bcc9-bb4bc16c2548};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>

Full example :

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
    <PropertyGroup>
      <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
      <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
      <ProjectGuid>{50E8AAEA-5CED-46BE-AC9A-B7EEF9F5D4C9}</ProjectGuid>
      <OutputType>Library</OutputType>
      <AppDesignerFolder>Properties</AppDesignerFolder>
      <RootNamespace>WpfApplication2</RootNamespace>
      <AssemblyName>WpfApplication2</AssemblyName>
      <TargetFrameworkVersion>v4.6.1</TargetFrameworkVersion>
      <FileAlignment>512</FileAlignment>
      <ProjectTypeGuids>{60dc8134-eba5-43b8-bcc9-bb4bc16c2548};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
      <WarningLevel>4</WarningLevel>
      <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
      <TargetFrameworkProfile />
    </PropertyGroup>
    <!-- ... -->