add a PushButton child widget

main.cc

@@ -1,14 +1,19 @@
 #include <QtGui>
 #include <QApplication>
-#include <QWidget>
+#include <QtWidgets>
 
 int main(int argc, char * argv[])
 {
     QApplication app(argc, argv);
+
     QWidget window;
     window.resize(600, 600);
     window.show();
     window.setWindowTitle("My Qt Application!");
 
+    QPushButton * button = new QPushButton("Press me", &window);
+    button->move(100, 100);
+    button->show();
+
     return app.exec();
 }