Thread work;
engine->working(true);
work.Run(callback(engine,&hEngine::getData));//-getData will do some UI refresh;
while (engine->working()){
  Refresh();//It cann't update UI here;
  Sleep(100);
}

begin ///this block run in the main thread
  create and run task thread......
  create and run task thread......
  Application.processmessage;///refresh UI immediately. In U++,it does not work.
  create and run task thread......
  create and run task thread......
  do some job......
end

begin ///this block run in the main thread
  create and run task thread......
  create and run task thread......
  while not result do begin ///wait the task thread result and refresh UI.  In U++, this will lock the GUI,other threads try to refresh the interface does not work
     sleep(100);
     Application.processmessage;///In delphi,this code is used to process GUI message in the main thread
  end;
  do some job......
end

void task_thread(){
  create and run task thread1
  create and run task thread2
  ..........
  
  create and run waiting thread
}
void wait_thread(){
  while (!result) Sleep(100);
  ...........
}

static bool Ctrl::IsWaitingEvent();
static bool Ctrl::ProcessEvent(bool *quit = NULL);
static bool Ctrl::ProcessEvents(bool *quit = NULL);