I am trying to set the visibility of the OverViewMap to false when I first instantiate it and then allow the user to toggle the visibility on and off using a button on a toolbar, but the OverViewMap does not honor it's visibility method. By default the OverViewMap is visible and using it's setVisible method to set it's visibility to false does nothing. When setting the visibility to true it opens a new blank window with the original OverViewMap still displayed.
I also tried to put the OverViewMap in a JFrame so I can add other buttons to is as I would like to be able to have interaction with the OverViewMap directly so a user can interact with the OverViewMap such as zooming to another area and having my main map update to that area.
overviewMap.setVisible(false);....this does hide the OverviewMap component. So it sounds like you're doing the right thing. I modified the OverviewMap toolkit sample to startup with the overviewMap visibility set to false, as a test, and it honored it.
I took that overview sample and am modifying it creating a class to create an overview map for my app. Not sure why it is opening another blank window when I toggle the visibility.