有關釋放Qwtplot 造成程式崩潰

[LeonSu]

作業系統 Ubuntu 18.04
Qt Version : 5.9.5
QMake Version: 3.1
GCC 7.4.0

各位前輩 大家好，
我在Qt上面建立了多個Qwtplot的元件，每一個元件都在原點設定一個點，當我在結束程式前，在解構子裡~MainWindow()釋放時，程式就會崩潰。其程式碼如下：
mainwindow.h

#include <QMainWindow>
#include <qwt_plot.h>
#include <qwt_plot_curve.h>
#include <qwt_plot_grid.h>
#include <qwt_plot_canvas.h>
#include <qwt_plot_curve.h>
#include <qwt_plot_grid.h>
#include <qwt_symbol.h>
#include <QPolygonF>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
private:
    Ui::MainWindow *ui;
    QwtPlot *qwtpt;
    QPolygonF *polygon;
    QwtPlotCurve *curve;
    QwtPlotGrid *grid;
    QwtSymbol *symbol;
};

mainwindow.cpp

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    int numpoints = 10;
    qwtpt = new QwtPlot[numpoints];
    polygon = new QPolygonF[numpoints];
    curve = new QwtPlotCurve[numpoints];
    grid = new QwtPlotGrid[numpoints];
    symbol = new QwtSymbol[numpoints];
    QString style = "color: white; ";
    QPolygonF initialpoint;
    initialpoint << QPointF(0.0f, 0.0f);
    int k;
    for(k = 0; k < numpoints; ++k){
        //plot
        qwtpt[k].setParent(ui->scrollArea);
        qwtpt[k].setGeometry(10, 20 + 181 * k, 760, 161);
        qwtpt[k].setAxisTitle(QwtPlot::xBottom, "points");
        qwtpt[k].setAxisTitle(QwtPlot::yLeft, "efficience %");
        qwtpt[k].setAxisScale(QwtPlot::xBottom, 0.0, 132);
        qwtpt[k].setAxisScale(QwtPlot::yLeft, 0.0, 100);
        qwtpt[k].setStyleSheet(style);
        //symbol
        symbol[k].setPen(QPen(Qt::red, 2));
        symbol[k].setStyle(QwtSymbol::Ellipse);
        symbol[k].setBrush(QBrush(Qt::yellow));
        symbol[k].setSize(QSize(8,8));
        //curve
        curve[k].setPen(Qt::blue, 4);
        curve[k].setRenderHint(QwtPlotItem::RenderAntialiased, true);
        curve[k].setSymbol(&symbol[k]);
        curve[k].attach(&qwtpt[k]);
        curve[k].setSamples(initialpoint);
        //grid
        grid[k].attach(&qwtpt[k]);
    }
}
MainWindow::~MainWindow()
{
    delete [] qwtpt;	//  Qt Debug 顯示在這行崩潰的
    delete [] polygon;
    delete [] curve;
    delete [] grid;
    delete [] symbol;
    delete ui;
}

如果，我沒有進行釋放的動作，則Qt Debug會顯示在~MainWindow()崩潰

若我將delete [] qwtpt;與delete [] curve;調換位置，則崩潰的點變成delete [] curve;這行

MainWindow::~MainWindow()
{
     delete [] curve;	//  Qt Debug 顯示在這行崩潰的
    delete [] polygon;
    delete [] qwtpt;
    delete [] grid;
    delete [] symbol;
    delete ui;
}

請問各位前輩是否有建議可以修正這個問題。
感謝各位。