docs: public static GlassPaneState showGlassPane(final Component source) {
          final Component focusOwner = KeyboardFocusManager.getCurrentKeyboardFocusManager()
                  .getFocusOwner();
          final RootPaneContainer rootPaneContainer = findRootPaneContainer(source);
          final Component glassPane = rootPaneContainer.getGlassPane();
          final MouseListener mouseListener = new MouseAdapter() {
          };
          final Cursor cursor = glassPane.getCursor();
          glassPane.addMouseListener(mouseListener);
          glassPane.setVisible(true);
          glassPane.requestFocus();
          glassPane.setCursor(new Cursor(Cursor.WAIT_CURSOR));
          return new GlassPaneState(glassPane, mouseListener, focusOwner, cursor);
      }