#include <QtGui/QApplication>
#include <QtGui/QMainWindow>
#include <QtGui/QFrame>
#include <QtGui/QVBoxLayout>
#include <QtGui/QLabel>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    /** We create a new QMainWindow */
    QMainWindow* mainWindow = new QMainWindow;
    /** We create a QFrame to work as
     * a central widget for the QMainWindow.
     */
    QFrame* centralWidget = new QFrame(mainWindow);
    /** The central widget is set with
      * the QMainWindow::centralWidget
      */
    mainWindow->setCentralWidget(centralWidget);
    /** We create a QVBoxLayout which provides us
      * positioning and widget resizing services.
      * QVBoxLayot does vertical layout so that widgets
      * are on above and below of each other.
      */
    QVBoxLayout* layout = new QVBoxLayout(centralWidget);
    QLabel* label = new QLabel("Hello World", centralWidget);
    /** Ask it to be aligned to center. */
    label->setAlignment(Qt::AlignCenter);
    /** Widgets are added to a layout with
      * simply calling QLayout::addWidget
      */
    layout->addWidget(label);
    /** We show the main window.
      */
    mainWindow->show();
    /** Start the event loop.
      */
    int returnValue = a.exec();
    /** Call the QObject::deleteLater() to a deferred delete.
      */
    mainWindow->deleteLater();
    return returnValue;
}