Bug 67890 [PropertiesView] Exception when entries added to properties view
bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/properties/PropertySheetViewer.java
/**
     * Creates a new tree item, sets the given entry or category (node)in
     * its user data field, and adds a listener to the node if it is an entry.
     * 
     * @param node
     *            the entry or category associated with this item
     * @param parent
     *            the parent widget
     * @param index
     *            indicates the position to insert the item into its parent
     */
    private void createItem(Object node, Widget parent, int index) {
        
        TreeItem item;
        if (parent instanceof TreeItem)
            item = new TreeItem((TreeItem) parent, SWT.NONE, index);
        else
            item = new TreeItem((Tree) parent, SWT.NONE, index);
        
        item.setData(node);
        
        if (node instanceof IPropertySheetEntry)
            ((IPropertySheetEntry) node)
                    .addPropertySheetEntryListener(entryListener);
        
        if (node instanceof IPropertySheetEntry)
            updateEntry((IPropertySheetEntry) node, item);
        else
            updateCategory((PropertySheetCategory) node, item);
    }