AccumulatedVisualContext Tree:
  [1] scroll_frame_id=1 (PaintableWithLines(BlockContainer<PRE>#out))
  [2] clip=[33,33 180x100]
    [3] scroll_frame_id=2 (PaintableWithLines(BlockContainer(anonymous)))

DisplayList:
SaveLayer@0
  CompositorWheelHitTestTarget@0 target_scroll_frame_index=0 rect=[0,0 800x600]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[0,0 800x21]
  CompositorWheelHitTestTarget@0 target_scroll_frame_index=0 rect=[20,20 204x154]
  FillRect@0 rect=[20,20 204x154] color=rgb(211, 211, 211)
  FillPath@0 path_bounding_rect=[20,20 204x154]
  CompositorWheelHitTestTarget@0 target_scroll_frame_index=2 rect=[32,32 182x102]
  CompositorScrollNode@0 scroll_frame_index=2 parent_scroll_frame_index=0 scrollport_rect=[33,33 180x100] max_scroll_offset=[120,100] is_viewport=false
  FillPath@0 path_bounding_rect=[32,32 182x102]
  CompositorWheelHitTestTarget@3 target_scroll_frame_index=2 rect=[33,33 300x200]
  FillRect@3 rect=[33,33 300x200] color=rgb(240, 128, 128)
  DrawGlyphRun@3 rect=[33,33 179x18] translation=[33,46.796875] color=rgb(0, 0, 0)
  PaintScrollBar@0
  PaintScrollBar@0
Restore@0