CombineWithNext
} else if (top->CombineWithNext(edit.Get())) {
virtual bool CombineWithNext(const UndoableEdit* next);
virtual bool CombineWithNext(const Command* next);
} else if (top->CombineWithNext(command)) {
virtual bool CombineWithNext(const Command* next);
virtual bool CombineWithNext(const Command* next);
virtual bool CombineWithNext(const Command* next);
} else if (top->CombineWithNext(command)) {