// Cache the entry <-> tree item relationship
entryToItemMap.put(node, item);
// Always ensure that if the tree item goes away that it's
// removed from the cache
item.addDisposeListener(new DisposeListener() {
public void widgetDisposed(DisposeEvent e) {
Object possibleEntry = e.widget.getData();
if (possibleEntry != null)
entryToItemMap.remove(possibleEntry);
}