Approve the selection, enabling the dialog to be closed. Called by
the JFileChooser's approveSelection() method. Use this
interface if you want to, for example, show a dialog asking
"Overwrite File X?" or similar.
selection - The selected file(s) at the time the user presses
the Open, Save or OK button
true if the selection is accepted, false if it is not and
the dialog should not be closed