#4 Deleted from disk tracks not removed from fs tree

[Mike]

When you delete tracks from the treeview in the file
system tab, they are not removed from the treeview,
though they are deleted from the disk.

* Reproduce

1. Select some files to delete in ds tree view
2. Hit Track -> Delete from disk
3. Files still appear in fs treeview

* Expected

Files are removed from tree view