def METHOD_NAME(self, url, no_url_callback=None, url_is_content=False):
    self.fv.assert_gui_thread()
    if url is None:
        self.entry.set_text('')
        if no_url_callback is None:
            self.fv.show_error("Couldn't load web page")
        else:
            no_url_callback()
    else:
        self.browse(url, url_is_content=url_is_content)