get: (k,dflt)=>F.storage.get(k,dflt),
        getBool: (k,dflt)=>F.storage.getBool(k,dflt),
        set: (k,v)=>F.storage.set(k,v),
        defaults:{
          "images-inline": !!F.config.chat.imagesInline,
          "edit-multiline": false,
          "monospace-messages": false,
          "chat-only-mode": false,
          "audio-notification": true,
        }
      },
      /** Plays a new-message notification sound IF the audio-notification
          setting is true, else this is a no-op. Returns this.
      */
      playNewMessageSound: function f(){
        if(this.settings.getBool('audio-notification',false)){
          try{
            if(!f.audio) f.audio = new Audio(F.rootPath+"chat-audio-received");
            f.audio.currentTime = 0;
            f.audio.play();
          }catch(e){
            console.error("Audio playblack failed.",e);
          }
        }
        return this;
      }
    };
    cs.e.inputCurrent = cs.e.inputSingle;
    /* Install default settings... */
    Object.keys(cs.settings.defaults).forEach(function(k){
      const v = cs.settings.get(k,cs);
      if(cs===v) cs.settings.set(k,cs.settings.defaults[k]);

    */
    cs.reportErrorAsMessage = function(/*msg args*/){
      const args = argsToArray(arguments);
      console.error("chat error:",args);
      const d = new Date().toISOString(),
            msg = {
              isError: true,
              xfrom: null,
              msgid: -1,
              mtime: d,
              lmtime: d,
              xmsg: args
            }, mw = new this.MessageWidget(msg);

      this.injectMessageElem(mw.e.body);
      mw.scrollIntoView();
    };

    cs.getMessageElemById = function(id){
      return qs('[data-msgid="'+id+'"]');
    };

     instance). These are modelled after FIELDSET elements but we
     don't use FIELDSET because of cross-browser inconsistencies in
     features of the FIELDSET/LEGEND combination, e.g. inability to
     align legends via CSS in Firefox and clicking-related
     deficiencies in Safari.
  */
  Chat.MessageWidget = (function(){
    /**
       Constructor. If passed an argument, it is passed to
       this.setMessage() after initialization.
    */
    const cf = function(){
      this.e = {
        body: D.addClass(D.div(), 'message-widget'),
        tab: D.addClass(D.span(), 'message-widget-tab'),
        content: D.addClass(D.div(), 'message-widget-content')
      };
      D.append(this.e.body, this.e.tab, this.e.content);
      this.e.tab.setAttribute('role', 'button');
      if(arguments.length){
        this.setMessage(arguments[0]);
      }
    };
    const theTime = function(d){
      return [d.getHours(),":",
              (d.getMinutes()+100).toString().slice(1,3)
             ].join('');
    };
    cf.prototype = {
      setLabel: function(label){
        return this;
      },
      scrollIntoView: function(){
        this.e.content.scrollIntoView();
      },
      setMessage: function(m){
        const ds = this.e.body.dataset;
        ds.timestamp = m.mtime;
        ds.lmtime = m.lmtime;
        ds.msgid = m.msgid;
        ds.xfrom = m.xfrom || '';
        if(m.xfrom === Chat.me){
          D.addClass(this.e.body, 'mine');
        }
        if(m.uclr){
          this.e.content.style.backgroundColor = m.uclr;
          this.e.tab.style.backgroundColor = m.uclr;
        }
        const d = new Date(m.mtime);
        D.clearElement(this.e.tab);
        var contentTarget = this.e.content;
        if(m.xfrom){
          D.append(
            this.e.tab,

            D.text(m.xfrom," #",(m.msgid||'???'),' @ ',theTime(d))


          );
        }else{/*notification*/
          D.addClass(this.e.body, 'notification');
          if(m.isError){
            D.addClass([contentTarget, this.e.tab], 'error');
          }
          D.append(
            this.e.tab,
            D.text('notification @ ',theTime(d))
          );
        }
        if( m.xfrom && m.fsize>0 ){
          if( m.fmime
              && m.fmime.startsWith("image/")
              && Chat.settings.getBool('images-inline',true)
            ){
            contentTarget.appendChild(D.img("chat-download/" + m.msgid));
            ds.hasImage = 1;
          }else{

            refresh:function(){
              const eMsg = this._eMsg;
              if(!eMsg) return;
              D.clearElement(this.e);
              const d = new Date(eMsg.dataset.timestamp);
              if(d.getMinutes().toString()!=="NaN"){
                // Date works, render informative timestamps
                const xfrom = eMsg.dataset.xfrom || 'server';
                D.append(this.e,
                         D.append(D.span(), localTimeString(d)," ",Chat.me," time"),
                         D.append(D.span(), iso8601ish(d)));
                if(eMsg.dataset.lmtime && xfrom!==Chat.me){
                  D.append(this.e,
                           D.append(D.span(), localTime8601(
                             new Date(eMsg.dataset.lmtime)

    },{
      label: "Message home/end buttons",
      boolValue: ()=>!Chat.e.btnMsgHome.classList.contains('hidden'),
      callback: ()=>Chat.toggleNavButtons()
    },{
      label: "Images inline",
      boolValue: ()=>Chat.settings.getBool('images-inline'),

      callback: function(){
        const v = Chat.settings.getBool('images-inline',true);
        Chat.settings.set('images-inline', !v);
        F.toast.message("Image mode set to "+(v ? "hyperlink" : "inline")+".");
      }
    },{
      label: "Audio notifications",
      boolValue: ()=>Chat.settings.getBool('audio-notification'),
      callback: function(){
        const v = Chat.settings.getBool('audio-notification');
        Chat.settings.set('audio-notification', !v);
        F.toast.message("Audio notifications "+(v ? "disabled" : "enabled")+".");
      }
    }];

    /**
       Rebuild the menu each time it's shown so that the toggles can
       show their current values.
    */
    settingsPopup.options.refresh = function(){

        if( m.msgid>Chat.mxMsg ) Chat.mxMsg = m.msgid;
        if( !Chat.mnMsg || m.msgid<Chat.mnMsg) Chat.mnMsg = m.msgid;
        if( m.mdel ){
          /* A record deletion notice. */
          Chat.deleteMessageElem(m.mdel);
          return;
        }
        if(!Chat._isBatchLoading && Chat.me!==m.xfrom && Chat.playNewMessageSound){
          Chat.playNewMessageSound();
        }
        const row = new Chat.MessageWidget(m);

        Chat.injectMessageElem(row.e.body,atEnd);
        if(m.isError){
          Chat._gotServerError = m;
        }
      }/*processPost()*/;
    }/*end static init*/
    jx.msgs.forEach((m)=>f.processPost(m,atEnd));