Screen does not refresh once minimised and then maximised

I have an event handler for a button. If the user selects the button a long running operation is executed from within the class that extends ActionListener. I do this by making the following call

SwingUtilities.invokeLater(class containing run method with long operation);

What I find is that if the user presses the button and whilst the backend operation is being actioned I minimise the window followed by maximising it, it redisplays but is totally grey and does not repaint until the long running operation completes.

Any pointers ?

Thanks

Justin

[588 byte] By [JUCKKYa] at [2007-10-2 2:09:03]