Bug 67890 [PropertiesView] Exception when entries added to properties view
bundles/org.eclipse.ui.views/src/org/eclipse/ui/views/properties/PropertySheetViewer.java
* Hides the categories.
     */
    
    void hideCategories() {
        isShowingCategories = false;
        categories = null;
        refresh();
    }
    /**
     * Hides the expert properties.
     */
    
    void hideExpert() {
        isShowingExpertProperties = false;
        refresh();
    }
    /**
     * Establish this viewer as a listener on the control
     */
    private void hookControl() {
        
        
        
        tree.addSelectionListener(new SelectionAdapter() {
            public void widgetDefaultSelected(SelectionEvent e) {
                handleSelect((TreeItem) e.item);
            }
        });
        
        tree.addMouseListener(new MouseAdapter() {