code: public final void setActiveWindow(ApplicationWindow window)
      {
          final ApplicationWindow old = this.activeWindow;
          this.activeWindow = window;
          if (getParent() != null) // let things ripple up
              getParent().setActiveWindow(window);
          getChangeSupport().firePropertyChange("activeWindow", old, window);
      }
docs: Set the currently active window. When a window gets focus, it will set itself
  as the current window of it's manager.
  
  @param window