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There are probably many different kinds of properties and you should check within your PropertyChangeListener which particular property was changed.
Perhaps the documentation can tell what kinds of...

I am not 100% sure how you fire the event so perhaps what I said earlier, that your event is fired on the SwingWorker was not true. It is still a good practice though to put the code into an...

Classes dont run on threads. Classes have absolutely nothing to do with threads.
Objects dont run on threads either. Bot these things are completely disconnected.

Each thread can run the methods...

You have to do what your propertyChange listener does within the EDT since you call repaint(). I dont know if this is the only issue but try it and come back if you still need help.