Have a look to this: http://www.mobilemotion.eu/?p=1537&lang=en
Summary:
Open the project’s manifest file (the one with the .csproj or .vbproj extension) in any text editor.
The top node usually contains several tags, one for each build configuration and a global one. In the global
node (the one without Condition attribute), search for
the sub-node or create one if it does not
exist. This node should contain two GUIDs:
FAE04EC0-301F-11D3-BF4B-00C04F79EFBC, which stands for a C# project,
and 60dc8134-eba5-43b8-bcc9-bb4bc16c2548 which stands for WPF. The
full line should look as follows:
<ProjectTypeGuids>{60dc8134-eba5-43b8-bcc9-bb4bc16c2548};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
(If you’re interested in details, codeproject holds a complete list of
potential project GUIDs:
http://www.codeproject.com/Reference/720512/List-of-Visual-Studio-Project-Type-GUIDs)
Reload the project in Visual Studio, and open the Add New Item wizard.
Since the project is now officially classified as WPF project, this
wizard should now contain the WPF window option. By the way, since
there is no WinForms project GUID that could be overwritten, this
approach does not harm the existing project components.
I just tried this approach for a VB.NET project and it works!
Using VB.NET obviously you have to edit above lines substituting the GUID from {FAE04EC0-301F-11D3-BF4B-00C04F79EFBC} to {F184B08F-C81C-45F6-A57F-5ABD9991F28F}