IWbs.Refresh Method
The task tree is represented by various properties in this IWbs instance, such as Root and ITask.SubTasks properties.
The majority of methods that manipulate the task tree will update the tree structure correctly and they don't require to call this method. For example, you can call ITask.CreateNewSubTask method on an ITask instance, let's call this instance T1. A new ITask instance T2 will be created and also added to the ITask.SubTasks property of the T1. As you can see, the task tree structure is kept in the correct state, so you don't have to call this method. (You still need to call IEstimate.CheckAndRepaint in this case to repaint the tasks in QDV, see the documentation for ITask.CreateNewSubTask)
On the other hand, there are methods, that for performance reasons, don't update the tree structure. For example, PasteBranchWithoutRefresh. You can call such methods multiple times and then call this Refresh method only once when you're done.
Remember, this method reads the WBS data from the current WBS workbook, so you need to make sure the workbook is repainted (even if invisible) with IEstimate.CheckAndRepaint method.
When this method rebuilds the task tree, the existing ITask instances are re-used if possible. So if you had a reference to an ITask instance, and then pasted some task branch under it, this instance is still valid and will contain the new branch in its ITask.SubTasks property after a call to this Refresh method.
