message: dont need to define tabindex
diff: @@ -16,7 +16,7 @@ export default class OpenButton extends React.Component {
  return (
  <span className="file-input">
  <input id={this.id} ref={(input) => { this.input = input; }} type="file" accept="application/json, text/html" onChange={this.handleChange} />
  - <label htmlFor={this.id} tabIndex="0" onFocus={() => {this.input.focus();}}><i className="btn-action si-open" /></label>
  + <label htmlFor={this.id} onFocus={() => {this.input.focus();}}><i className="btn-action si-open" /></label>
  </span>
  );
  }
  