Well the subject line is pretty much the whole post. In the control area for the freehand tool are two check boxes labeled 'smoothness' and 'magnetism' the second one being under the 'assistant' check box. Checking these doesn't seem to affect the behavior of the line art tool at all.

If they worked what would they do?

I'm using version 2.0.2 on Ubuntu 64 bit Karmic. It's fairly broken in lots of ways. And lack of a manual makes it a no starter even if it were stable. Going back to 1.6 soon. I'm just curious.

DS

Smoothness applies make the stroke smoother while painting. It's a very light effect, that is only can only be observed if you make a long curve.

The assistant option can be used with assitants like ruler. You can insert a ruler assistent with the ruler assistent tool. That will show a ruler on the canvas and the magnetism setting will control how the freehand tool snaps to that ruler.