I have a GnomeCanvas Group that I'm trying to rotate (in 2D).

I know which direction the "top" of the group should be pointing.

My initial attempt was 
        affine = Art::Affine.new([Math.cos(180), -Math.sin(180), 0, 
Math.sin(180), Math.cos(180), 0])
        @group.affine_absolute(affine)

That was to rotate the object 180 degrees, but it didn't work too
well.  I'm pretty new to all this matrix transformation / graphical
stuff.  Could someone tell me if I'm on the right track?

Thanks,
Joe Van Dyk