#include using namespace Upp; struct MyAppWindow : TopWindow { Button button; void Click() { PromptOK("You have clicked the button!"); } typedef MyAppWindow CLASSNAME; MyAppWindow() { Title("My application with button"); Add(button.LeftPos(10, 100).TopPos(10, 30)); button.SetLabel("Click me!"); button <<= THISBACK(Click); } }; GUI_APP_MAIN { MyAppWindow app; app.Run(); }