void ViewModel_imports::add_item() {
	Noesis::Ptr<Item_model> new_item = *new Item_model(); // Create new item
	mListBoxItems->Add(new_item.GetPtr()); // Add item
	new_item->SetIsChecked(is_checked); // !!! change value after addition. Check mark is shown
}

int ViewModel_imports::check_item(NsSize i, bool state) {
	mListBoxItems->Get(i)->SetIsChecked(state); // Check mark not updated
	return 0;
}

void CheckItem::SetIsChecked(bool check) {
	_propertyChanged(this, NSS(mChecked));
	if (mChecked != check) {
		mChecked = check;
	}
}
class Item_model : public CheckItem {
// ...
}

void CheckItem::SetIsChecked(bool check) {
	if (mChecked != check) {
		mChecked = check;
		_propertyChanged(this, NSS(mChecked));
	}
}
class Item_model : public CheckItem {
// ...
}

ViewModel_imports::check_item(NsSize i, bool state) {
	Item_model* item = mListBoxItems->Get(i);
	item->SetIsChecked(state);
	mListBoxItems->CollectionChanged().Invoke(this, NotifyCollectionChangedEventArgs(
		NotifyCollectionChangedAction::NotifyCollectionChangedAction_Reset,
		i, i, item, item));
	return 0;
}

class CheckItem : public Item, public INotifyPropertyChanged {
public:
	virtual void SetIsChecked(bool) {
			if (mChecked != check) {
			mChecked = check;
			_propertyChanged(this, NSS(IsChecked));
		}
	}
	virtual bool GetIsChecked() const {
		return mChecked;
	}
	PropertyChangedEventHandler& PropertyChanged() {
		return _propertyChanged;
	}
protected:
	NsBool mChecked;
	t_callback_func callback;
private:
	PropertyChangedEventHandler  _propertyChanged;
	NS_IMPLEMENT_INLINE_REFLECTION(CheckItem, BaseComponent) {
		NsMeta<TypeId>("CheckItem");
		NsImpl<INotifyPropertyChanged>();
		NsProp("IsChecked", &CheckItem::GetIsChecked, &CheckItem::SetIsChecked);
	}
};

class Item_model : public CheckItem {
private:
	NS_IMPLEMENT_INLINE_REFLECTION(Item_model, BaseComponent) {
		NsMeta<TypeId>("ListItem");
		NsProp("IsChecked", &Item_model::GetIsChecked, &Item_model::SetIsChecked);
	}
};