Wt

#include <Wt/WApplication.h>
#include <Wt/WBootstrap5Theme.h>
#include <Wt/WContainerWidget.h>
#include <Wt/WDialog.h>
#include <Wt/WPushButton.h>
#include <Wt/WTimer.h>

class DialogApplication : public Wt::WApplication
{
public:
  DialogApplication(const Wt::WEnvironment& env)
      : Wt::WApplication(env)
  {
    setTheme(std::make_shared<Wt::WBootstrap5Theme>());
    // Create the "work" button
    auto workBtn = root()->addNew<Wt::WPushButton>("Push me for work.");
    workBtn->clicked().connect(this, &DialogApplication::performWork);

    doneSignal_.connect(this, &DialogApplication::setWorkDialogHidden);
  }

private:
  Wt::WDialog* workDialog_ = nullptr;
  Wt::Signal<> doneSignal_;

  void performWork()
  {
    if (!workDialog_) {
      workDialog_ = root()->addChild(std::make_unique<Wt::WDialog>());
      workDialog_->setWindowTitle("Performing work");
      workDialog_->contents()->addNew<Wt::WText>("Doing something for 2 seconds");
    }

    workDialog_->setHidden(false);

    Wt::WTimer* timer = addChild(std::make_unique<Wt::WTimer>());
    timer->timeout().connect(this, &DialogApplication::doneWork);
    timer->setInterval(std::chrono::seconds(2));
    timer->setSingleShot(true);
    timer->start();
  }

  void doneWork()
  {
    doneSignal_.emit();
  }

  void setWorkDialogHidden()
  {
    workDialog_->setHidden(true);
  }
};

int main(int argc, char **argv)
{
  return Wt::WRun(argc, argv, [](const Wt::WEnvironment& env) {
    return std::make_unique<DialogApplication>(env);
  });
}