PropertyHandle :: CheckValidity - Check property handle validity

Subordinated property handles might become invalid, when the the instance in the parent handle has changed its type or when reopening the parent handle for any reason. Usually, the situation is automatically handled by ValidateNode(), which is called internally in most cases before executing property handle functions. In this case, however, the application will not notice, that the property handle has changed its access node and other subordinated property handles became invalid.

Calling CheckValidity() checks whether reopen the property handle becomes necessary and enable the application to react properly.