code: def create_region_from_border_clip(self, onerror = None):
      
  
      rid = self.display.allocate_resource_id()
      CreateRegionFromBorderClip(
          display = self.display,
          onerror = onerror,
          opcode = self.display.get_extension_major(extname),
          region = rid,
          window = self,
          )
  
      # FIXME: create Region object and return it
      return rid
docs: Create a region of the border clip of the window, i.e. the area
      that is not clipped by the parent and any sibling windows.