<Subtype>Designer</Subtype> Added then removed by Visual Studio on load/unload

This might be related to what files you have open in the saved solution state. I ran into this problem in VS2010 and found that if I close the solution while an .xml file was open in the editor, then on the subsequent re-open of the solution, the project containing that .xml file would get this <SubType>Designer</SubType> line added. If I close the solution without that file open, though, it does not try to add that line on the following re-open.

This has been an issue in at least 3 editions of Visual Studio, 2008, 2010 and now 2012. It is logged as a bug in Microsoft Connect but the MS answer is "We have recorded your request but are not planning on fixing this at this time." Suggest you up vote the bug report as it is still active and might get a better response from MS with enough up votes.

I am encountering the same problem in my ASP.NET web application's .csproj file:

<ItemGroup>
  <Content Include="site.master" />
  <Content Include="Web.config">
    <SubType>Designer</SubType>
  </Content>
</ItemGroup>

Versus:

<ItemGroup>
  <Content Include="site.master" />
  <Content Include="Web.config" />
</ItemGroup>

My annoyance with this issue is due to revision control changes as well. The issue seems to be present in VS 2005/2008/2010. Have found the following question on Microsoft forums, but the answer is not clear.

• What is <SubType>Designer</SubType> for in .csproj?

I hope that a VS setting causes it, in which case, I will like you know when I find out what that setting is.