+ if (n == 0) {
+ return;
+ }
+
+ {
+ UndoRedoSignaller exception_safe_signaller (*this);
+
+ while (n--) {
+ if (UndoList.size() == 0) {
+ return;
+ }
+ UndoTransaction* ut = UndoList.back ();
+ UndoList.pop_back ();
+ ut->undo ();
+ RedoList.push_back (ut);