def METHOD_NAME(self, plugin=None, no_url_callback=None):
    from ginga.doc.download_doc import get_doc
    self.fv.assert_nongui_thread()
    self.fv.gui_do(self._load_doc, WAIT_HTML, url_is_content=True)
    def _dl_indicator(count, blksize, totalsize):
        pct = (count * blksize) / totalsize
        msg = 'Downloading: {:.1%} complete'.format(pct)
        self.fv.gui_do(self.entry.set_text, msg)
    # This can block as long as it takes without blocking the UI.
    if self.settings.get('offline_doc_only', False):
        url = None  # DEBUG: Use this to force offline mode.
    else:
        url = get_doc(logger=self.logger, plugin=plugin,
                      reporthook=_dl_indicator)
    self.fv.gui_do(self._load_doc, url, no_url_callback=no_url_callback)