static TreeItem createItem (TreeItem parent, int itemIndex) {
	TreeItem newItem = null;
	if (parent == null) {	/* root level item */
		newItem = new TreeItem (tree, SWT.NONE);
	} else {
		newItem = new TreeItem (parent, SWT.NONE);
	}
	String indexString = String.valueOf (itemIndex); 
	newItem.setText(new String[] {
		indexString + 'a', indexString + 'b', indexString + 'c'});
	return newItem;
}