anchor.diff:  
     // - - - - - - - - - - - - - - - - - - - - - - - -
   
  -  var showLatestNoDiff = function() {
  -    var lastTag = -1;
  +  const showLatestNoDiff = () => {
  +    const lastTag = -1;
       param.wasTag = lastTag;
       param.nowTag = lastTag;
       refresh();
  
positive.code: 
    // - - - - - - - - - - - - - - - - - - - - - - - -
  
    var showFile = function(filenameId) {
      var filename =  $('#radio_' + filenameId);
      filename.click();
      filename.scrollIntoView({ direction: 'vertical' });
    };
  
    // - - - - - - - - - - - - - - - - - - - - - - - -
  
    var show = function(tag) {
      // preserve diff on/off state
      param.wasTag = tag - (diffCheckBox().is(':checked') ? 1 : 0);
      param.nowTag = tag;
  
negative.code: 
    // - - - - - - - - - - - - - - - - - - - - - - - -
  
    const refresh = () => {
      if (inDialog()) {
        reviewRefresh();
      } else {
  