Description of problem:
Just browsing on Public zone

Version-Release number of selected component:
firewall-config-0.3.4-1.fc19

Additional info:
reporter:       libreport-2.1.10
cmdline:        /usr/bin/python /usr/bin/firewall-config
executable:     /usr/bin/firewall-config
kernel:         3.10.11-200.fc19.x86_64
runlevel:       N 5
type:           Python
uid:            1000

Truncated backtrace:
firewall-config:1630:onChangeZone:TypeError: 'NoneType' object is not iterable

Traceback (most recent call last):
  File "/usr/bin/firewall-config", line 1630, in onChangeZone
    for item in interfaces:
TypeError: 'NoneType' object is not iterable

Local variables in innermost frame:
masquerade: False
name: 'time-exceeded'
_services: []
default: False
_icmpblocks: []
interfaces: None
args: (<TreeSelection object at 0x384a2d0 (GtkTreeSelection at 0x33c8b70)>,)
iter: None
self: <__main__.FirewallConfig object at 0x3291a90>
sources: []
builtin: False
icmpblocks: []
rules: []
services: ['ssh']
active_zone: 'dmz'
ports: []
forward_ports: []