for this case, values expected:
bo.x(20) = margin-left + border-left-width of HTMLHtmlElement
bo.y(20) = margin-top + border-top-width of HTMLHtmlElement
bo.width(500) = width
bo.height(50) = height
values got:
bo.x(0),bo.y(0) = left,top corner relative to inner left,top corner of HTMLHtmlElement
bo.width(500) = width
bo.height(50) = height