If the file chooser's working directory is removed from
under it, the next time you try to bring it back up, an
NPE is thrown, and from that point you can never
display the file chooser again.
Steps to reproduce:
1. Open the file chooser.
2. Create a temporary directory, such as "/tmp/foo".
3. Create and save a file in that directory, such
4. Outside of RText, go and remove the
5. Try to open or save a file. The file chooser doesn't
come up; this is because an NPE is thrown.