setPopupCallback: function(callback){
        this.e.tab.addEventListener('click', callback, false);
        return this;
      },
      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');
        }
        this.e.content.style.backgroundColor = m.uclr;
        this.e.tab.style.backgroundColor = m.uclr;

    };
    Object.keys(dropEvents).forEach(
      (k)=>Chat.e.inputFile.addEventListener(k, dropEvents[k], true)
    );
    return bxs;
  })()/*drag/drop*/;

  const tzOffsetToString = function(off){
    const hours = Math.round(off/60), min = Math.round(off % 30);
    return ''+(hours + (min ? '.5' : ''));
  };
  const pad2 = (x)=>('0'+x).substr(-2);
  const localTime8601 = function(d){
    return [
      d.getYear()+1900, '-', pad2(d.getMonth()+1), '-', pad2(d.getDate()+1),
      'T', pad2(d.getHours()),':', pad2(d.getMinutes()),':',pad2(d.getSeconds()),
      'Z', tzOffsetToString(d.getTimezoneOffset())
    ].join('');
  };
    
  Chat.submitMessage = function(){
    const fd = new FormData(this.e.inputForm)
    /* ^^^^ we don't really want/need the FORM element, but when
       FormData() is default-constructed here then the server
       segfaults, and i have no clue why! */;
    const msg = this.inputValue();
    if(msg) fd.set('msg',msg);
    const file = BlobXferState.blob || this.e.inputFile.files[0];
    if(file) fd.set("file", file);

    if( msg || file ){
      fd.set("lmtime", localTime8601(new Date()));
      fetch("chat-send",{
        method: 'POST',
        body: fd
      });
    }
    BlobXferState.clear();
    Chat.inputValue("").inputFocus();

      ' ',ff.pad(d.getHours()),':',ff.pad(d.getMinutes()),
      ':',ff.pad(d.getSeconds())
    ].join('');
  };
  /* Returns an almost-ISO8601 form of Date object d. */
  const iso8601ish = function(d){
    return d.toISOString()
      .replace('T',' ').replace(/\.\d+/,'').replace('Z', ' Zulu');
  };
  /* Event handler for clicking .message-user elements to show their
     timestamps. */
  const handleLegendClicked = function f(ev){
    if(!f.popup){
      /* Timestamp popup widget */
      f.popup = new F.PopupWidget({
        cssClass: ['fossil-tooltip', 'chat-message-popup'],
        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;
            D.append(this.e,
                     D.append(D.span(), localTimeString(d)," ",Chat.me," time"),
                     D.append(D.span(), iso8601ish(d)));
            if(xfrom!==Chat.me){
              D.append(this.e,
                       D.append(D.span(), localTime8601(
                         new Date(eMsg.dataset.lmtime)
                       )," ",xfrom," time"));
            }
           }else{
            // Date doesn't work, so dumb it down...
            D.append(this.e, D.append(D.span(), eMsg.dataset.timestamp," Zulu"));
          }
          const toolbar = D.addClass(D.div(), 'toolbar');
          D.append(this.e, toolbar);
          const btnDeleteLocal = D.button("Delete locally");
          D.append(toolbar, btnDeleteLocal);
          const self = this;
          btnDeleteLocal.addEventListener('click', function(){