Description of problem:
When create a new virtual network, fill in IPv4 address, forward until the last step, Then click Back to re-fill in IPv4 address, click next, but DHCP range value is still no change

Version-Release number of selected component (if applicable):
virt-manager-0.6.1-14.el5

How reproducible:
Always

Steps to Reproduce:
1. Create a new virtual network, fill in IPv4 address, next, until the last step
2. In last step click Back, Back to re-fill in the IPv4 address
3. Click Next, check DHCP range value
  
Actual results:
The first time fill in IPv4 address, the DHCP range will change correspondingly. But Back to re-fill in IPv4 address, the DHCP range will keep as the first time

Expected results:
DHCP range should change correspondingly once IPv4 address is changed.

Additional info: