Bug 159550 [Viewers] Deprecate TableTreeViewer
The underlying SWT-controls of TableTreeViewer (TableTree,TableTreeItem,TableTreeEditor) are deprecated and so should TableTreeViewer I think.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TableTreeViewer.java
return tableViewerImpl.isCellEditorActive();
    }
    /* (non-Javadoc)
     * Method declared in AbstractTreeViewer.
     */
    protected Item newItem(Widget parent, int flags, int ix) {
        TableTreeItem item;
        if (ix >= 0) {
            if (parent instanceof TableTreeItem) {
				item = new TableTreeItem((TableTreeItem) parent, flags, ix);
			} else {
				item = new TableTreeItem((TableTree) parent, flags, ix);
			}
        } else {
            if (parent instanceof TableTreeItem) {
				item = new TableTreeItem((TableTreeItem) parent, flags);
			} else {
				item = new TableTreeItem((TableTree) parent, flags);
			}
        }
        return item;
    }
    /* (non-Javadoc)
     * Method declared in AbstractTreeViewer.
     */
    protected void removeAll(Control widget) {
        ((TableTree) widget).removeAll();
    }
    /**
     * Sets the cell editors of this table viewer.