code: func (v *Button) GetImage() (*Widget, error) {
  	c := C.gtk_button_get_image(v.native())
  	if c == nil {
  		return nil, nilPtrErr
  	}
  	obj := glib.Take(unsafe.Pointer(c))
  	return wrapWidget(obj), nil
  }
docs: // GetImage() is a wrapper around gtk_button_get_image().