public void createSelectionListener() {
        selectionListener = new SelectionAdapter() {
            @Override
                        public void widgetSelected(SelectionEvent event) {
                Widget widget = event.widget;
                if (widget == addButton) {
                    addPressed();
                } else if (widget == removeButton) {
                    removePressed();
                } else if (widget == upButton) {
                    upPressed();
                } else if (widget == downButton) {
                    downPressed();
                } else if (widget == list) {
                    selectionChanged();
                }
            }
        };
    }