REG: Error message is not displayed when tried to uncheck the mozilla check box (mozilla is launched)

Tested build : mustang promoted build 72
Tested OS : windows

Steps to reproduce :

1. Install mustang build 72
2. clear cache
3. Launch java control panel
4. Go to advanced tab -> check the Mozilla, IE browser check boxes and click apply
Don't close java control panel
5. Launch mozilla browser
6. In the java control panel, uncheck the mozilla check box and click apply button

There should be a error message "Unable to change browser settings"
But nothing is displayed

Note : This was working fine till mustang PIT b72 but this is not happening from promoted b72