Curses, I just recently thought of thing project and was planning it out.
If you want, the file manager is totally modular and you can feel free to go ahead and use it in one of your own mods as a resource.
Just call the function promptUserFile( DefaultDirectory, Callback, Mode ) in interface.cs
//promptUserFile is the only function your program should need to call
//%default - default directory
//%callback - your function that takes arguments %path and %description
//%mode - modes accepted are "save", "load", "savebls", "loadbls", and ""
function promptUserFile(%default, %callback, %mode)
{
...