Add Reference to Visual Studio 2005

I have installed .Net Framework 3.5 in my box (not 3.0) and WCSF for a ASP.NET project based on WCSF. When I tried to use Guidance Package Manger's Add Page Flow Project recipe I got an error and failed to add the project.

I wondered why it failed. It must use some kind template to add project. I then found the template project which has the following references but I cannot see them in my VS Add Reference Dialog window:

<Reference Include="System.Workflow.Activities" />
<Reference Include="System.Workflow.ComponentModel" />
<Reference Include="System.Workflow.Runtime" />

I think that is the reason I get the failure. My direct reaction was that I thought .Net 3.5 may not include or install 3.0 assembly files. That's wrong. From VS Add Reference list, I can see that System.WorkFlowServices.dll is located in C:\Program Files\Reference Assemblies\Microsoft\Framework\v3.5\, and others which are not in VS's Add Reference window are in ...\v.30 folder.

It must be some settings such as environment or registry settings which make these assembly files visible in VS. I can find where those settings are. Anyway, cut the story in short, I found a msdn link about How to: Add ore Remove Reference in Visual Studio 2005. This web page does provide information on how to add customized assemblies in VS by setting windows registries. I followed the instruction I found that the NUnit and MbUnit assembly files I installed are set in the registry and they are in VS Add Reference window. Here are examples of NUnit 2.4.3 and MbUnit in the current user registry:

[HKEY_CURRENT_USER\SOFTWARE\Microsoft\.NETFramework\AssemblyFoldersEx\NUnit 2.4.3]@="c:\Program Files\NUnit 2.4.3\bin\"
[HKEY_CURRENT_USER\SOFTWARE\Microsoft\.NETFramework\v2.0.50727\AssemblyFoldersEx\MbUnit]@="c:\Program Files\MbUnit\"

Notice that NUnit is not related to any version while MbUnit is under .Net v2.0.50727. According to the msdn, if you add assembly location folders in HKEY_LOCAL_MACHINE in the same way, any user in the pc then can see these assemblies in VS.

Those are settings for third party to add their assemblies to VS 2005's Add Reference window. However, I still can not find any thing bout Microsoft assembly settings. I know where assembly files are, but I don't know what settings to cause them visible in the VS 2005's Add Reference window. Maybe Microsoft does not want people to mess up third party programs with Microsoft ones.

Anyway, I finally find a way to get them visible in VS 2005. I installed Visual Studio 2005 extensions for .NET Framework 3.0 (Windows Workflow Foundation). The installation did some magic settings and I can add Page Flow Project without any failure and I do see these v3.0 WowkFlow assembly files in VS 2005.