Bug 184755 [DataBinding] internal tree content provider does not work
I broke the tree content providers while trying to update them to use TreePaths. It would be good to have a working implementation again...
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/internal/databinding/internal/viewers/UnorderedTreeNode.java
boolean willBeStale = children.isStale();
        if (willBeStale != isStale) {
            isStale = willBeStale;
            
            contentProvider.changeStale(isStale? 1 : -1);
        }
    }
    
    /**
     * @return <code>true</code> if the children of this node will change soon
     */
    public boolean isStale() {
        return isStale;
    }
    /**
     * Returns true if the viewer should show a plus sign for expanding this 
     * node. 
     * 
     * @return <code>true</code> if this node may have children
     */
    public boolean shouldShowPlus() {
        if (children == null) {
            return true;
        }
        if (!listeningToChildren && !prefetchEnqueued) {
            prefetchEnqueued = true;
            contentProvider.enqueuePrefetch(this);
        }
        return !listeningToChildren || hasPendingNode || !children.isEmpty();
    }