I don't know if I'm doing this right, but when I run the following code in the Python Fu Console in Gimp 2.8.8 on Windows, and try to choose anything from the dropdown menu, I get an error saying "pythonw.exe has stopped working", and the Window and Python Console crash. The only way around it, is to use Return on the keyboard to select anything from the menu, rather than click it.

import gtk
window = gtk.Window()
dialog = gtk.FileChooserDialog( "Test", None, gtk.FILE_CHOOSER_ACTION_SELECT_FOLDER, (gtk.STOCK_CANCEL, gtk.RESPONSE_CANCEL, gtk.STOCK_OPEN, gtk.RESPONSE_OK))
button = gtk.FileChooserButton(dialog)
window.add(button)
window.show_all()

When I run the gtk.FileChooserDialog, I get the following warnings:

C:\Program Files\GIMP 2\lib\gimp\2.0\plug-ins\python-console.py:1: Warning: Attempt to add property GtkSettings::gtk-can-change-accels after class was initialised
  #!/usr/bin/env python
C:\Program Files\GIMP 2\lib\gimp\2.0\plug-ins\python-console.py:1: Warning: Attempt to add property GtkSettings::gtk-menu-popup-delay after class was initialised
  #!/usr/bin/env python
C:\Program Files\GIMP 2\lib\gimp\2.0\plug-ins\python-console.py:1: Warning: Attempt to add property GtkSettings::gtk-menu-popdown-delay after class was initialised
  #!/usr/bin/env python

I mainly use Linux, and when I tried the exact same code there in Gimp 2.8.8, I don't get any warnings, and it actually works like it's supposed to. The difference is that my home folder shows up as a default selection, while on windows it just says (None), though the drop down menu is populated by a few default locations (my home folder, Destkop, C:, etc.).