onClickClearKeywordsFile() {
    parent.postMessage({ pluginMessage: {
        msg: 'clippy-file-cleared',
      }}, '*');
  }

  function toNumber(str, def) {
    let num = parseInt(str, 10);
    if (isNaN(num)) {
      return def;
    }
    return num;
  }

  function setGridMarginsSummary() {
    let valuesEqual = 
      gridMarginLeft.value == gridMarginRight.value &&
      gridMarginLeft.value == gridMarginTop.value &&
      gridMarginLeft.value == gridMarginBottom.value;
    gridMarginsAll.value = val