layer at (0,0) size 800x600
  RenderCanvas at (0,0) size 800x600
layer at (0,0) size 800x600
  RenderBlock {HTML} at (0,0) size 800x600
    RenderBody {BODY} at (8,8) size 784x584 [border: (2px solid #FF0000)]
      RenderBlock {DIV} at (14,14) size 756x28
        RenderBR {BR} at (0,0) size 0x28
      RenderBlock {DIV} at (14,42) size 756x28
        RenderText {TEXT} at (0,0) size 12x28
          text run at (0,0) width 12: "x"
selection is CARET:
start:      position 0 of child 1 {TEXT} of child 2 {DIV} of root {BODY}
upstream:   position 0 of child 2 {DIV} of root {BODY}
downstream: position 0 of child 1 {TEXT} of child 2 {DIV} of root {BODY}