ui.Canvas implements getSaveCount() which returns the size of the internal save(Layer) stack, but it does not provide any methods to use that information. Typically a save/restore type of graphics object will provide a restoreToCount(save_count) method to quickly roll back a number of outstanding/unmatched save methods - often useful when the execution of a method had some of its save or saveLayer calls invoked conditionally so that a single "restore to the save count when we started" call can replace a nest of conditional restores at the end of that sequence.