D.addClass(this,'hidden');
      cs.clearFilters();
    }, false);
    return cs;
  })()/*Chat initialization*/;

  /**
     An experiment in history navigation: when a message numref is
     An experiment in history navigation: when a message numtag is
     clicked, we push the origin message onto the history and
     set up the back button to return to that message.
  */
  if(0) window.onpopstate = function(event){
    console.debug("onpopstate event",event.state, event);
    if(event.state && event.state.msgId){
  window.onpopstate = function(event){
    const msgid = Chat.numtagHistoryStack.pop();
    if(msgid){
      const e = Chat.setCurrentView(Chat.e.viewMessages).
            querySelector('.message-widget[data-msgid="'+event.state.msgId+'"]');
      console.debug("Popping history back to",event.state, e);
            querySelector('.message-widget[data-msgid="'+msgid+'"]');
      //console.debug("Popping history back to",msgid, e);
      if(e){
        Chat.MessageWidget.scrollToMessageElem(e);
        //F.page.setPageTitle("Fossil Chat #"+event.state.msgId);
        return;
      }
    }
    Chat.scrollMessagesTo(1);
  };
  Chat.numtagHistoryStack = [
    /* Relying on the pushHistory() state object for holding
       the message ID is completely misbehaving, not giving
       us the expected state object when window.onpopstate
       is triggered (plus, the browser persists it, which
       introduces its own problems). Thus we use our own
       stack of message IDs for history navigation purposes. */];

  /** If e or one of its parents has the given CSS class, that element
      is returned, else falsy is returned. */
  const findParentWithClass = function(e, className){
    while(e && !e.classList.contains(className)){
      e = e.parentNode;
    }
    return e;
  };
  
  /** To be passed each MessageWidget's top-level DOM element
      after initial processing of the message, to set up
      hashtag references. */
      hashtag and numtag references. */
  const setupHashtags = function f(elem){
    if(!f.$click){
      f.$click = function(ev){
        /* Click handler for hashtags */
        const tag = ev.target.dataset.hashtag;
        if(tag){
          Chat.setHashtagFilter(

        if(tag){
          const e = Chat.e.viewMessages.querySelector(
            '.message-widget[data-msgid="'+tag+'"]'
          );
          if(e){
            Chat.MessageWidget.scrollToMessageElem(e);
            //Set up window.history() state...
            const p = 1 ? false : findParentWithClass(ev.target, 'message-widget');
            const p = 0 ? false : findParentWithClass(ev.target, 'message-widget');
            if(p){
              const state = {msgId: p.dataset.msgid};
              console.debug("Pushing history for msgid", state);
              const rc = window.history.pushState(state, "?");
              console.debug("History length =",window.history.length, rc);
              Chat.numtagHistoryStack.push(p.dataset.msgid);
              const rc = window.history.pushState(state, "");
              //console.debug("Pushing history for msgid", state);
              //console.debug("Chat.numtagHistoryStack =",Chat.numtagHistoryStack);
            }
          }else{
            F.toast.warning("Message #"+tag+" not found in loaded messages.");
          }
        }
      };
    }