Bug 161425 [Viewers] TableTreeViewer => EditingSupport broken
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TableTreeViewer.java
protected Item[] getChildren(Widget o) {
		if (o instanceof TableTreeItem) {
			return ((TableTreeItem) o).getItems();
		}
		if (o instanceof TableTree) {
			return ((TableTree) o).getItems();
		}
		return null;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.viewers.AbstractTreeViewer#getChild(org.eclipse.swt.widgets.Widget,
	 *      int)
	 */
	protected Item getChild(Widget widget, int index) {
		if (widget instanceof TableTreeItem) {
			return ((TableTreeItem) widget).getItem(index);
		}
		if (widget instanceof TableTree) {
			return ((TableTree) widget).getItem(index);
		}
		return null;
	}
	/**
	 * Returns the column properties of this viewer. The properties must
	 * correspond with the columns of the table control. They are used to
	 * identify the column in a cell modifier.
	 * 
	 * @return the list of column properties