How to make (.cs) code files expand / collapse underneath another code file in Visual Studio solution explorer?

In Visual Studio 2008/2010 it's possible to place a series of simple .cs code files underneath another .cs file in solution explorer. This behavior is similar to how you see files arranged when adding a WPF UserControl to the solution, where instead a single .cs file can collapse/expand underneath the .xaml file.

How do you make the solution arrange开发者_开发百科 files this way? I've already looked in some of the obvious places, like the file properties pane, the solution and .csproj property pages.

I'm not sure there is a way to do this through the Visual Studio UI.

You can do it by manually editing the .csproj file. The trick is to add the <DependentUpon> XML tag to the element you want to appear under another. For example

<Compile Include="Settings.Designer.cs">
  <AutoGen>True</AutoGen>
  <DependentUpon>Settings.settings</DependentUpon>
  <DesignTimeSharedInput>True</DesignTimeSharedInput>
</Compile>

You have to edit the .csproj file and add this:

<Compile Include="Form1.Designer.cs">
  <DependentUpon>Form1.cs</DependentUpon>
</Compile>

Or install a plugin like VSCommands in Visual Studio 2010.