}else{
        e = this.getMessageElemById(id);
      }
      if(!e || !id) return false;
      else if(e.$isToggling) return;
      e.$isToggling = true;
      const content = e.querySelector('.content-target');
      if(!content){
        console.warn("Should not be possible: trying to toggle text",
                     "mode of a message with no .content-target.", e);
        return;
      }
      if(!content.$elems){
        content.$elems = [
          content.firstElementChild, // parsed elem
          undefined // plaintext elem
        ];
      }else if(content.$elems[1]){
        // We have both content types. Simply toggle them.
        const child = (
          content.firstElementChild===content.$elems[0]
            ? content.$elems[1]
            : content.$elems[0]
        );
        D.clearElement(content);
        if(child===content.$elems[1]){
          /* When showing the unformatted version, inject a
             copy-to-clipboard button. This is a workaround for
             mouse-copying from that field collecting twice as many
             newlines as it should (for unknown reasons). */
          const cpId = 'copy-to-clipboard-'+id;
          /* ^^^ copy button element ID, needed for LABEL element
             pairing.  Recall that we destroy all child elements of
             `content` each time we hit this block, so we can reuse
             that element ID on subsequent toggles. */
          const btnCp = D.attr(D.addClass(D.span(),'copy-button'), 'id', cpId);
          F.copyButton(btnCp, {extractText: ()=>child._xmsgRaw});
          const lblCp = D.label(cpId, "Copy unformatted text");
          lblCp.addEventListener('click',()=>btnCp.click(), false);
          D.append(content, D.append(D.addClass(D.span(), 'nobr'), btnCp, lblCp));
        }
        delete e.$isToggling;
        D.append(D.clearElement(content), child);
        D.append(content, child);
        return;
      }
      // We need to fetch the plain-text version...
      const self = this;
      F.fetch('chat-fetch-one',{
        urlParams:{ name: id, raw: true},
        responseType: 'json',
        onload: function(msg){
          content.$elems[1] = D.append(D.pre(),msg.xmsg);
          content.$elems[1]._xmsgRaw = msg.xmsg/*used for copy-to-clipboard feature*/;
          self.toggleTextMode(e);
        },
        aftersend:function(){
          delete e.$isToggling;
          Chat.ajaxEnd();
        }
      });

                    e = n;
                  }
                  eMsg.scrollIntoView();
                }
              ));
              const toolbar2 = D.addClass(D.div(), 'toolbar');
              D.append(this.e, toolbar2);
              if(eMsg.querySelector('.content-target')){
                /* ^^^ messages with only an embedded image have no
                   .content-target area. */
              D.append(toolbar2, D.button(
                "Toggle text mode", function(){
                  self.hide();
                  Chat.toggleTextMode(eMsg);
                }));
                D.append(toolbar2, D.button(
                  "Toggle text mode", function(){
                    self.hide();
                    Chat.toggleTextMode(eMsg);
                  }));
              }
              if(eMsg.dataset.xfrom){
                /* Add a link to the /timeline filtered on this user. */
                const timelineLink = D.attr(
                  D.a(F.repoUrl('timeline',{
                    u: eMsg.dataset.xfrom,
                    y: 'a'
                  }), "User's Timeline"),

     and/or the file attachment field to the server. If both are
     empty, this is a no-op.
  */
  Chat.submitMessage = function f(){
    if(!f.spaces){
      f.spaces = /\s+$/;
      f.markdownContinuation = /\\\s+$/;
      f.spaces2 = /\s{3,}$/;
    }
    this.setCurrentView(this.e.viewMessages);
    const fd = new FormData();
    const fallback = {msg: this.inputValue()};
    var msg = fallback.msg.trim();
    var msg = fallback.msg;
    if(msg && (msg.indexOf('\n')>0 || f.spaces.test(msg))){
      /* Cosmetic: trim whitespace from the ends of lines to try to
      /* Cosmetic: trim most whitespace from the ends of lines to try to
         keep copy/paste from terminals, especially wide ones, from
         forcing a horizontal scrollbar on all clients. This breaks
         markdown's use of blackslash-space-space for paragraph
         continuation, but *not* doing this affects all clients every
         time someone pastes in console copy/paste from an affected
         platform. We seem to have narrowed to the console pasting
         problem to users of tmux together with certain apps (vim, at
         problem to users of tmux. Most consoles don't behave
         that way. */
         a minimum). Most consoles don't behave that way.

         We retain two trailing spaces so that markdown conventions
         which use end-of-line spacing aren't broken by this
         stripping.
      */
      const xmsg = msg.split('\n');
      xmsg.forEach(function(line,ndx){
        if(!f.markdownContinuation.test(line)){
          xmsg[ndx] = line.trimRight();
          xmsg[ndx] = line.replace(f.spaces2, '  ');
        }
      });
      msg = xmsg.join('\n');
    }
    if(msg) fd.set('msg',msg);
    const file = BlobXferState.blob || this.e.inputFile.files[0];
    if(file) fd.set("file", file);