preference dialog fails to change select action options

When attempting to change the "one window open" and "multiple windows open" options in the group button tab of the preference dialog, the selected option will appear in the pulldown menu but the actual function won't change. If the preference dialog is closed and re-opened, the original option will then be in the pulldown menu as if nothing happened. Running dbx_preference.py in a terminal gives:

Traceback (most recent call last):
  File "/usr/bin/dbx_preference.py", line 945, in cb_changed
    GCONF_CLIENT.set_string(GCONF_DIR+'/'+setting_name, smd[value])
UnboundLocalError: local variable 'setting_name' referenced before assignment

when a change is attempted.

I've attached a patch which replaces setting_name with the appropriate string literals.