btnDelete.setEnabled( viewer.getTable( ).getSelectionIndex( ) != -1 );
btnDelete.setEnabled( isFileSystemFile( ) && viewer.getTable( ).getSelectionIndex( ) != -1 );
	private void updateButtonState( )	{		getOkButton( ).setEnabled( viewer.getTable( ).getSelectionCount( ) > 0 );		btnDelete.setEnabled( viewer.getTable( ).getSelectionIndex( ) != -1 );	}