We've been using new Tree View API to provide structured view of F# projects - in F# project files needs to be ordered according to compilation order so this additional view gives users better information about their project. We also include in the view list of project references, and assembly references so it's really similar to the Visual Studio solution explorer.

It looks like following:

As I've mentioned - ordering of files is really important for the F# projects, and we provide couple of helper commands to manage it (move file up/down etc). Those commands work more or less, but I don't think it's best UX.
I think it would be super nice if users had ability to use normal drag and drop to manipulate the order - just as they are able to manipulate files in normal file explorer (drag and drop files to move them to subfolder for example)