Is it possible to add files to a CMake generated solution folder in Visual Studio?

This question is more or less a warmup of this question:

how to get cmake to add files to msvcs solution tree

It never got a valid answer so I want to repose it slightly different:

Is it possible to use the cmake solution folders that where introduced with cmake 2.8.3 to add files directly to the vs solution? I want to do the cmake equivalent of VS->Solution->Add->Existing Item. So my file will appear in a folder that belongs to the solution and not to a project.

I found examples how the solution folders can be used to group targets into folders with code like this:

set_property( GLOBAL PROPERTY USE_FOLDERS ON)
set_property(TARGET ${TARGET_NAME} PROPERTY FOLDER "Test") 

So can I add a file instead of a target to the folder?

With the upcoming cmake version 4.0.0 (currently available as release candidate 4.0.0-rc5) it is going to be possible to add arbitrary files to the Solution in VS. This is done through the newly added VS_SOLUTION_ITEMS Property, see here: VS_SOLUTION_ITEMS

This is a directory property, so it has to be applied on the same directory as your initial project() call is made in.

Usage example:

set_directory_properties(PROPERTIES 
    VS_SOLUTION_ITEMS 
        ./conanfile.py 
        ./cmake/marcos.cmake
        # etc..
)