smoothOrigin:true
element doesn't jump when origin changes.
smoothOrigin:false
element jumps when origin changes.

Initial scale of the boxes is scale:2 with their transform origin in the upper left corner, transformOrigin:"left top". The red circles indicate the transformOrigin position.

smoothOrigin:false is actually the "proper" implementation based on the SVG and CSS specs, but smoothOrigin:true looks more natural and smooth.