internal CDODrawRequest toNative()
 {
     CDODrawRequest nReq = new CDODrawRequest();
     nReq.bottom = bottom;
     nReq.top = top;
     nReq.left = left;
     nReq.right = right;
     nReq.windowHandle = hdc;
     return nReq;
 }
 public static extern void cdo_draw(CDOH handle,
     ref CDODrawRequest request);