What does the NM Applet button do?

["James K. Williams" <james k williams comcast net>]

When you click left on the NetworkManager applet, there is a list of connections, and you must select one of the radio buttons there to get networking working. What exactly does selecting that radio button do?

Here's why I ask. I don't really need NM at all, because I can edit all the network configuration files by hand and then restart network services with

# services network restart

This should be enough to bring networking up, but it's not: I still have to select one of those radio buttons in the NM applet. To try to determine what pressing that button does, I have checked services before and after, and there is no difference. Also, I have checked the config files before and after, and they are not changed. So what happens under the hood when I select one of the buttons in the applet? Why doesn't networking come back on until I press it?

I'm using NetworkManager 0.7.1 on Fedora 9.

Thanks.