gets the status of the undo command . concode_field_sep int cursor concode_elem_sep ArrayList<Memento> mementoStateHistory concode_elem_sep int maxHistorySize concode_field_sep boolean isRedo concode_elem_sep void undo concode_elem_sep void redo concode_elem_sep void addState
boolean function ( ) { return mementoStateHistory . size ( ) > 0 && cursor > 0 ; }