Bug 153993 [Viewers] Common Baseclass for Tree/TableEditorImpl
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TableTreeViewer.java
/**
     * Internal table viewer implementation.
     */
    private TableEditorImpl tableViewerImpl;
    /**
     * This viewer's table tree control.
     */
    private TableTree tableTree;
    /**
     * This viewer's table tree editor.
     */
    private TableTreeEditor tableTreeEditor;
    /**
     * Private implementation class.
     */
    class TableTreeViewerImpl extends TableEditorImpl {
    	
        /**
         * @param viewer the tabletree viewer working for
         */
        public TableTreeViewerImpl(TableTreeViewer viewer) {
            super(viewer);
        }
        Rectangle getBounds(Item item, int columnNumber) {
            return ((TableTreeItem) item).getBounds(columnNumber);
        }
        int getColumnCount() {