When you create a animated dashed line or connector e.g.
        {10 . 5 . Color red . 0 . 3} 
and then clone it via the halo to apx 20 instances the UI becomes
really sluggish. I believe Squeak redraws each line on each step,
which is of course a lot of work. 

OTOH it changes only a few pixels on the screen so I thought maybe
someone has an idea how one could speed this up.