undo method
Undo the last operation
Implementation
bool undo() {
if (!canUndo || _applyEdit == null) return false;
final operation = _undoStack.removeLast();
final inverse = operation.inverse();
_isUndoRedoInProgress = true;
try {
_applyEdit!(inverse);
_redoStack.add(operation);
} finally {
_isUndoRedoInProgress = false;
}
notifyListeners();
return true;
}