Custom XAML designer in custom projects type Visual Studio

I made a custom XAML designer as http://code.msdn.microsoft.com/windowsdesktop/Designer-View-Over-XML-20a81f17

I have a question: how to make custom designer worked only on some types of projects (eg custom type of projects), and all the other projects designer used by default.

In file VsTemplateDesignerPackage.cs have:

// Microsoft Visual Basic Project 
[EditorFactoryNotifyForProject("{F184B08F-C81C-45F6-A57F-5ABD9991F28F}", 
EditorFactory.Extension, GuidList.guidXmlChooserEditorFactory)]
// Microsoft Visual C# Project
[EditorFactoryNotifyForProject("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}", 
EditorFactory.Extension, GuidList.guidXmlChooserEditorFactory)]

I add:

//CustomProjectType
[EditorFactoryNotifyForProject("{GUID CustomProjectType}",
 EditorFactory.Extension, GuidList.guidXmlChooserEditorFactory)]

But it does not work. This leads to the fact that the custom designer for this extension is used in all types of projects.

How do I make a custom designer to open *.XAML files only in custom projects?