anchor.diff:      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);
  
positive.code:   const makeDiffType = (diff) => {
      if (diff === '&nbsp;') { return diff; }
      const $div = $('<div>', { class:`diff-type-marker ${diff.type}` });
      if (diff.type === 'renamed') {
        const tip = `was<span class="diff-filename unchanged">${diff.old_filename}</span>`;
        $div.attr('data-tip', tip);
      }
      return outerHTML($div);
    };
  
    // - - - - - - - - - - - - - - - - - - - - - - - -
  
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
  