public override void PaintBackground(IVwGraphics vg, PaintTransform ptrans)
{
base.PaintBackground(vg, ptrans);
PaintTransform childTrans = ptrans.PaintTransformOffsetBy(Left, Top);
for (Box box = FirstVisibleBox(vg, ptrans); box != null && !IsAfterVisibleBoxes(box, vg, ptrans); box = box.Next)
{
box.PaintBackground(vg, childTrans);
}
}