code: public void onCopyToClipboard(ActionEvent actionEvent) {
          Clipboard systemClipboard = Clipboard.getSystemClipboard();
          ClipboardContent content = new ClipboardContent();
          content.putString(loggingArea.getText());
          systemClipboard.setContent(content);
      }
docs: A shortcut button to get the contents of the logger window into the clipboard.
  @param actionEvent ignored