#include <CtrlLib/CtrlLib.h>
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();
}