title: How do i find if a window is opened on swing
body: <p>I have a problem with my application where the user will open more than one window at a time. And i have added dispose() method to call on closing the window. Now i should keep at-least one window open all the time so that the application does not hides without closed fully. If you don't understand read the following scenario:  </p>
  
  <p>I have window A and window B opened at the same time. Now i can close either window A or Window B but not both. In other words window B should be allowed to close only if window A is opened and vice versa. How do i do this in swing ??</p>