code: func DrawingAreaNew() (*DrawingArea, error) {
  	c := C.gtk_drawing_area_new()
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	obj := glib.Take(unsafe.Pointer(c))
  	return wrapDrawingArea(obj), nil
  }
docs: // DrawingAreaNew is a wrapper around gtk_drawing_area_new().