hashtag:{
          activeTag: undefined,
          match: function(tag){
            return !this.activeTag || tag===this.activeTag;
          },
          matchElem: function(e){
            return !this.activeTag
              || !!e.querySelector('[data-hashtag="'+this.activeTag+'"]');
          }
        },
        current: undefined/*gets set to current active filter*/
      },
      /** Gets (no args) or sets (1 arg) the current input text field value,
          taking into account single- vs multi-line input. The getter returns
          a string and the setter returns this object. */

  /** To be passed each MessageWidget's top-level DOM element
      after initial processing of the message, to set up
      hashtag 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(
            tag===Chat.filter.hashtag.activeTag
              ? false : tag
          );
        }
      };
      f.$clickNum = function(ev){
        /* Click handler for #NNN references */
        const tag = ev.target.dataset.numtag;
        if(tag){
          const e = Chat.e.viewMessages.querySelector(
            '.message-widget[data-msgid="'+tag+'"]'
          );
          if(e){
            Chat.MessageWidget.scrollToMessageElem(e);
          }else{
            F.toast.warning("Message #"+tag+" not found in loaded messages.");
          }
        }
      };
    }
    elem.querySelectorAll('[data-hashtag]').forEach(function(e){
      e.dataset.hashtag = e.dataset.hashtag.toLowerCase();
      e.addEventListener('click', f.$click, false);
    })

    elem.querySelectorAll('[data-numtag]').forEach(
      (e)=>e.addEventListener('click', f.$clickNum, false)
    )
  }/*setupHashtags()*/;

  /**
     Custom widget type for rendering messages (one message per
     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

                    D.append(
                      D.addClass(D.div(), 'toolbar'),
                      D.button(
                        "Message in context",
                        function(){
                          self.hide();
                          Chat.clearFilters();
                          Chat.MessageWidget.scrollToMessageElem(eMsg);

                        })
                    )
                  );
                }/*jump-to button*/
              }
              const tab = eMsg.querySelector('.message-widget-tab');
              D.append(tab, this.e);

        }/*end static init*/
        let theMsg = ev.target;
        while( theMsg && !theMsg.classList.contains('message-widget')){
          theMsg = theMsg.parentNode;
        }
        if(theMsg) f.popup.show(theMsg);
      }/*_handleLegendClicked()*/
    }/*MessageWidget.prototype*/;
    /** Assumes that e is a MessageWidget element, ensures that
        Chat.e.viewMessages is visible, scrolls the message,
        and animates it a bit to make it more visible. */
    cf.scrollToMessageElem = function(e){
      if(e.firstElementChild){
        Chat.setCurrentView(Chat.e.viewMessages);
        e.scrollIntoView(false);
        Chat.animate(e.firstElementChild, 'anim-flip-h');
      }
    };
    return cf;
  })()/*MessageWidget*/;

  const BlobXferState = (function(){/*drag/drop bits...*/
    /* State for paste and drag/drop */
    const bxs = {