AccumulatedVisualContext Tree:
  [1] scroll_frame_id=1 (PaintableWithLines(BlockContainer<PRE>#out))

DisplayList:
SaveLayer@0
  CompositorWheelHitTestTarget@0 target_scroll_frame_index=0 rect=[0,0 800x600]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[0,0 800x53]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[8,8 784x32]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[8,8 784x32]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[8,8 32x32]
  DrawCompositorSurface@1 dst_rect=[8,8 32x32]
Restore@0
