AccumulatedVisualContext Tree:
  [0] transform=[1,0,0,1,0,0] origin=(0,0) (ViewportPaintable(Viewport<#document>))
    [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 800x51]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[8,8 784x30]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[8,8 147x30]
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[8,8 28.59375x30]
  FillRect@1 rect=[8,8 29x30] color=rgb(0, 0, 0)
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[37.59375,8 28.59375x30]
  FillRect@1 rect=[38,8 28x30] color=rgb(0, 0, 0)
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[67.1875,8 28.59375x30]
  FillRect@1 rect=[67,8 29x30] color=rgb(0, 0, 0)
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[96.78125,8 28.59375x30]
  FillRect@1 rect=[97,8 28x30] color=rgb(0, 0, 0)
  CompositorWheelHitTestTarget@1 target_scroll_frame_index=0 rect=[126.375,8 28.59375x30]
  FillRect@1 rect=[126,8 29x30] color=rgb(0, 0, 0)
Restore@0

