This is some test of widgets added during page loading rather than on page load. The two scrollbars are added with position absolute ( normal addChild), while the third one is added using addInflowChild() and thus follows the page content flow.
Vertical:
ratioX
ratioY
set height: 50, 100, 150, 200
set ratioY: 0, 0.5, 1

Horizontal:
ratioX
ratioY
set width: 50, 100, 150, 200
set ratioX: 0, 0.5, 1


Here goes a table. Amazing.
Box:
ratioX
ratioY
set size: 50, 100, 150, 200
set ratioX: 0, 0.5, 1
set ratioY: 0, 0.5, 1

End of page. wow

Note: some problems while sliding the knob in the inline scrollbar, but must be something about the event coordinate calculation. Mozilla resizes the table cell while dragging the knob. Oh my. Anyway.