undo.cpp

case 'u':
{
  for (int i = 0; i < n; i++) {
    if (!_app.commandStack().empty() && _app.commandStack().top()->canUndo()) {
      _app.commandStack().top()->undo();
      _app.commandStack().pop();
    }
  }
  if (_app.commandStack().empty()) {
    _app.textView().buffer().setUnsavedChanges(false);
    _app.updateViews();
    _app.updateStatusView("Already at oldest change");
  }
  break;
}