Open a terminal. In a subfolder of home, like home/myfolder, create a file (e.g.
touch home/myfolder/testfile). 

Open gedit and go to "File"/"Open...". Navigate to /home/myfolder. 

In the terminal, remove the file with "rm testfile:.

In gedit's filechooser, click on the "myfolder" button in the path bar to
refresh the file list. The removed file (testfile) still appears in the list, 
but with a blank icon, and you get plenty of warnings : 
GLib-GObject-WARNING **: invalid uninstantiatable type `(null)' in cast to
`GtkFileFolderGnomeVFS'

Now, in the path bar, click on "home", then on "nyfolder" : you cannot select
"myfolder" anymore, instead you get the warnings :
GLib-GObject-CRITICAL **: g_object_ref: assertion `G_IS_OBJECT (object)' failed

With gtk+ and gnome-vfs CVS.