Hi Michael,
You probably should add CSIDL_MY[MUSIC|VIDEO|PICTURES] to the 'folders' array in shellpath.c's _SHRegisterUserShellFolders function. This would generate the appropriate registry entries. With the current implementation those would all point to the user's home directory. In _SHGetDefaultValue, you could check for 'My Music', 'My Videos' and 'My Pictures' folders in $HOME and, if they are present, map to those instead.
So I will do...
Thanks for helping!
Markus