Older VS (using C++) allowed (as far as I can remember) grouping of related sources to sort of groups. Something like Headers group, Sources group etc.
Is it possible to group files in such way in VS2013 using C#? Even if it does mean manual edit of the project xml files.
The only way I have found is to create a Folder, but the requirement is to have flat structure on disk and tree structure in project.
Edit:
It is called Filter in the C++ projects.
And it seems impossible for C# as already discussed here.