anchor.diff:  
     // - - - - - - - - - - - - - - - - - - - - - - - -
     const buildDiffFilenameHandlers = (diffs) => {
  -    const clicked = [];
       diffs.forEach(diff => {
         const filename = diffFilename(diff);
  +      const $filename = $(`#radio_${diff.id}`, $reviewPage);
         diff.section_index = 0;
  -      $(`#radio_${diff.id}`).click(() => {
  +      diff.clicked = false;
  +      $filename.click(() => {
           selectLineCounts(filename);
  -        selectFilename(diff.id);
  +        selectFilename($filename);
           selectFile(filename);
  -        whenReClickedScrollToNextDiffChunk(clicked, diff, filename);
  -        param.filename = filename;
  -        clicked.push(filename);
  +        whenReClickedScrollToNextDiffChunk(diff, filename);
         });
       });
     };
  
positive.code:       diff.section_index += 1;
        diff.section_index %= diff.section_count;
      }
    };
  
    // - - - - - - - - - - - - - - - - - - - - - - - -
  
negative.code:     $(`[id="${filename}_diff_div"]`).show();
    };
  
    const whenReClickedScrollToNextDiffChunk = (diff, filename) => {
      const firstClick = (filename) => !diff.clicked;
      const reClicked = (filename) => param.filename === filename;
      if (diff.section_count > 0 && (firstClick(filename) || reClicked(filename))) {
        const $diffSheet = $(`[id="diff_file_content_for_${filename}"]`);
  