Thanks global goon,
I think I know why the pen isn't working right. Looks like a little bug in the module input connector. Jorge also spotted another little problem when trying to extend what you'd done to make it refresh as you move the sliders.
As a workaround you can add a String component just before the Line component Pen input. This will ensure that the conversion from String to Pen is doen properly.
Shouldn't be too difficult to fix these problems so we'll most probably just do them now and so they will be in the next incremental release.
Sorry about that.