message: Added conditional rendering of the sandbox so it doesn't happen on Firefox
diff: @@ -96,6 +96,14 @@ if (browser.windows) {
  firefox57WorkaroundForBlankPanel();
  }
  +if (parser(window.navigator.userAgent).browser.name !== "Firefox") {
  + const sandbox = document.createElement("iframe");
  + sandbox.setAttribute("id", "sandbox");
  + sandbox.setAttribute("src", "sandbox.html");
  + sandbox.setAttribute("style", "display: none");
  + document.body.appendChild(sandbox);
  +}
  +
  @DragDropContext(HTML5Backend)
  @observer export default class Panel extends React.Component {
  constructor(props) {
  