CollapsedBorderValue top = collapsedTopBorder(c);
CollapsedBorderValue right = collapsedRightBorder(c);
CollapsedBorderValue bottom = collapsedBottomBorder(c);
CollapsedBorderValue left = collapsedLeftBorder(c);
_collapsedPaintingBorder = new BorderPropertySet(top, right, bottom, left);
// Give the extra pixel to top and left.
top.setWidth((top.width()+1)/2);
right.setWidth(right.width()/2);
bottom.setWidth(bottom.width()/2);
left.setWidth((left.width()+1)/2);
_collapsedLayoutBorder = new BorderPropertySet(top, right, bottom, left);
_collapsedBorderTop = top;
_collapsedBorderRight = right;
_collapsedBorderBottom = bottom;
_collapsedBorderLeft = left;