anchor.diff:    const makeDiffType = (diff) => {
       if (diff === '&nbsp;') { return diff; }
       const $div = $('<div>', { class:`diff-type-marker ${diff.type}` });
  +    let hoverTip = '';
       if (diff.type === 'renamed') {
  -      const tip = `was<span class="diff-filename unchanged">${diff.old_filename}</span>`;
  -      $div.attr('data-tip', tip);
  +      hoverTip += oldFilenameTip(diff);
  +    }
  +    if (diff.chunkCount > 0) {
  +      if (hoverTip != '') { hoverTip += '<br/>'; }
  +      hoverTip += chunkCountTip(diff);
  +    }
  +    if (hoverTip != '') {
  +      $div.attr('data-tip', hoverTip);
       }
       return outerHTML($div);
  +  };
  +
  +  const oldFilenameTip = (diff) => {
  +    return `was<span class="diff-filename renamed">${diff.old_filename}</span>`;
  +  };
  +
  +  const chunkCountTip = (diff) => {
  +    return `diff chunk count == ${diff.chunkCount}`;
     };
   
     // - - - - - - - - - - - - - - - - - - - - - - - -
  
positive.code:     diffs.forEach(diff => {
        const filename = diffFilename(diff);
        const $filename = $(`#radio_${diff.id}`, review.page);
        diff.chunkIndex = 0
        diff.chunkCount = diff.lines.reduce((n,line) => n + (line.type === 'section'), 0);
        diff.hasBeenClicked = false;
        $filename.click(() => {
          selectLineCounts(filename);
          selectFilename($filename);
  
negative.code:     tip += '<span class="diff-line-count-icon same">=</span> number of deleted,added,unchanged lines.<br/>';
      tip += '<hr/>';
      tip += 'click a filename to review it.<br/>';
      tip += 'reclick the filename to cycle through its diff-chunks.<br/>';
      tip += '<hr/>';
      tip += '<span class="diff-type-marker unchanged"></span><span class="diff-filename unchanged">unchanged-file</span><br/>';
      tip += '<span class="diff-type-marker created"></span><span class="diff-filename created">created-file</span><br/>';
      tip += '<span class="diff-type-marker deleted"></span><span class="diff-filename deleted">deleted-file</span><br/>';
      tip += '<span class="diff-type-marker changed"></span><span class="diff-filename changed">changed-file</span>';
      tip += ' hover over <span class="diff-type-marker changed"></span> for diff chunk count<br/>';
      tip += '<span class="diff-type-marker renamed"></span><span class="diff-filename renamed">renamed-file</span>';
      tip += ' hover over <span class="diff-type-marker renamed"></span> for old filename';
      const $div = $('<div>', {
        class: 'diff-help-icon',
        'data-tip': tip
  