Watch the picture form one sampling step at a time and stop a run that is
going wrong. Step Preview needs no wires and shows whichever sampler is
working, with Stop and Stop all. Save Image and Save Video get a steps
switch, off by default, that shows the steps where the saved picture goes,
with a Stop button.
A queued workflow that shows its steps asks ComfyUI for the auto preview
method for that run, only when no method was chosen in the frontend or on
the command line.
ausboss