File Type Manager not working

[BlackDex]

Using the latest ubuntu-tweak 0.6 for oneiric i can't use the "File Type Manager". When i want to change, add an other program for some file-type i can push buttons what i wan't it is not working.
Also i can't resize the dialogs/windows.

When running via CLI i get the following error messages.
------
(ubuntu-tweak:12798): Gtk-WARNING **: Unknown property: GtkDialog.has-separator

(ubuntu-tweak:12798): Gtk-WARNING **: Unknown property: GtkDialog.has-separator
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/ubuntutweak/admins/filetype.py", line 376, in on_add_button_clicked
    app = Gio.AppInfo(we)
TypeError: GInterface.__init__() takes exactly 0 arguments (1 given)

(ubuntu-tweak:12798): Gtk-WARNING **: Unknown property: GtkDialog.has-separator

(ubuntu-tweak:12798): Gtk-WARNING **: Unknown property: GtkDialog.has-separator
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/ubuntutweak/admins/filetype.py", line 376, in on_add_button_clicked
    app = Gio.AppInfo(we)
TypeError: GInterface.__init__() takes exactly 0 arguments (1 given)
------