}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(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);
                  }));
              }
              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;
    if(msg && (msg.indexOf('\n')>0 || f.spaces.test(msg))){
      /* 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
         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.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);