code: function focusToFirstTh(sq, $table) {
    const range = sq.getSelection();
  
    range.selectNodeContents($table.find('th')[0]);
    range.collapse(true);
    sq.setSelection(range);
  }
docs: Focus to first th
  @param {Squire} sq Squire instance
  @param {jQuery} $table jQuery wrapped table element