Maximise button on the window frame... affecting my resize logic

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Hi all,
Recently, i integrated jogl with NEWT.
My Program extends from FRAME.
My problem now is that when the user clicks on the MAximise button, my screen resizing logic seems to fail!
I wanted the screen to be propertional to the dimension i have set.
Hence, i wrote a simple logic and handle the resize issue when the users were to resize the window (*drag the bottom right of the window)
It does Black Padding to either the sides or the top and bottom depending on the aspect ratio.
But my current logic fails when the windows is maximised...

Is there any one who has a better logic?