PropertyHandle :: Reset - Reset instance
The function resets the current selection in the property handle, i.e. the selection is canceled without storing the last updates (->Cancel()). Since the function is canceling the selection all subordinated property handles will cancel the selection as well.
Than the function will reread the instance from the database (->Get()). Subordinated property handles remain in unselected state.
The function returns 0, if the currently selected instance could be reread. It returns 1, if there was an error canceling or rereading the instance. However the function does not cancel and reread, it also returns 0, if no instance was positioned or the positioned instance was nor dirty.
The instance is re-read by identity. Than the key is extracted from the instance to check, whether the instance is still member of the collection. If the key is not found in the index the function tries to locate the instance in the index by identity. This might take a little while, but in the other case generic instances will cause problems when the generic type in the instance differs from the generic type of the index. If no instance could be found, the function returns an error (but no SDB-Error).