By definition, a message box is modal, and will always suspend the application that initiated the message box. The only solution is to close the message box.
That being said, there are situations where its advantageous to write your own message box function, especially in un-attended operations. Used in combination with a timer, you can display your own custom message, but still allow execution to continue. If the message box is not acknowledged within some given time period, your app can log the event to a file for later review, and get rid of the box. Good Luck
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As a circle of light increases so does the circumference of darkness around it. - Albert Einstein