protected void installPreviewPanel(@NotNull JPanel previewPanel) {
    previewPanel.setLayout(new BorderLayout());
    previewPanel.add(getEditor().getComponent(), BorderLayout.CENTER);
    previewPanel.setBorder(new AbstractBorder() {
      private static final int LEFT_WHITE_SPACE = 2;

      @Override
      public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
        Editor editor = getEditor();
        if (editor instanceof EditorEx) {
          g.setColor(((EditorEx)editor).getBackgroundColor());
          g.fillRect(x + 1, y, LEFT_WHITE_SPACE, height);
        }
        g.setColor(OnePixelDivider.BACKGROUND);
        g.fillRect(x, y, 1, height);
      }

      @Override
      public Insets getBorderInsets(Component c, Insets insets) {
        insets.set(0, 1 + LEFT_WHITE_SPACE, 0, 0);
        return insets;
      }
    });
  }
protected void installPreviewPanel(@NotNull JPanel previewPanel)