#include <qapplication.h>#include <qmainwindow.h>#include <qwt_counter.h>#include <qtoolbar.h>#include <qlabel.h>#include <qlayout.h>#include "data_plot.h"class MainWindow: public QMainWindow{public:    MainWindow()    {        QToolBar *toolBar = new QToolBar(this);        toolBar->setFixedHeight(80);#if QT_VERSION < 0x040000        setDockEnabled(TornOff, true);        setRightJustification(true);#else        toolBar->setAllowedAreas(Qt::TopToolBarArea | Qt::BottomToolBarArea);#endif        QWidget *hBox = new QWidget(toolBar);        QLabel *label = new QLabel("Timer Interval", hBox);        QwtCounter *counter = new QwtCounter(hBox);        counter->setRange(-1.0, 100.0, 1.0);        QHBoxLayout *layout = new QHBoxLayout(hBox);        layout->addWidget(label);        layout->addWidget(counter);        layout->addWidget(new QWidget(hBox), 10); // spacer);#if QT_VERSION >= 0x040000        toolBar->addWidget(hBox);#endif        addToolBar(toolBar);        DataPlot *plot = new DataPlot(this);        setCentralWidget(plot);        connect(counter, SIGNAL(valueChanged(double)),            plot, SLOT(setTimerInterval(double)) );        counter->setValue(20.0);    }};int main(int argc, char **argv){    QApplication a(argc, argv);    MainWindow mainWindow;#if QT_VERSION < 0x040000    a.setMainWidget(&mainWindow);#endif    mainWindow.resize(600,400);    mainWindow.show();    return a.exec(); }