Wt

If a dialog is shown during rendering then no content is displayed. Here is an example:

class Model : public Wt::WStringListModel
{
public:
    Wt::cpp17::any data(const Wt::WModelIndex& index, Wt::ItemDataRole role = Wt::ItemDataRole::Display) const override
    {
        if (role == Wt::ItemDataRole::Display)
        {
            Wt::WMessageBox::show("caption", "text", Wt::StandardButton::Ok);
        }

        return Wt::WStringListModel::data(index, role);
    }
};

class Application : public Wt::WApplication
{
public:
    Application(const Wt::WEnvironment& env);
};

Application::Application(const Wt::WEnvironment& env)
    : Wt::WApplication(env)
{
    auto tableView = root()->addNew<Wt::WTableView>();
    auto model = std::make_shared<Model>();
    model->addString("Row");
    tableView->setModel(model);
}