custom widget in delegate

[anbu01]

Hi,
I need to show custom widget(lineEdit +PushButton) on double click of QTreeview so i have created my own Delegate but for some reason the widget is not shown.I have createEditor() method override in delegate.Here is a sample Code i have done.I have not implemented the paint method to render the data but my problem is the widget doesn't shown when create editor called.Guide me on this

MainWindow.cpp

QStandardItemModel *model = new QStandardItemModel;
    for (int row = 0; row < 4; ++row) {
        for (int column = 0; column < 4; ++column) {
            QStandardItem *item = new QStandardItem(QString("row %0, column %1").arg(row).arg(column));
            model->setItem(row, column, item);
        }
    }
 
    QTreeView *veiw = new QTreeView(this);
    MyDelegate *del = new MyDelegate;
    veiw->setItemDelegate(del);
    veiw->setModel(model);
 
    setCentralWidget(veiw);

QStandardItemModel *model = new QStandardItemModel;
    for (int row = 0; row < 4; ++row) {
        for (int column = 0; column < 4; ++column) {
            QStandardItem *item = new QStandardItem(QString("row %0, column %1").arg(row).arg(column));
            model->setItem(row, column, item);
        }
    }

    QTreeView *veiw = new QTreeView(this);
    MyDelegate *del = new MyDelegate;
    veiw->setItemDelegate(del);
    veiw->setModel(model);

    setCentralWidget(veiw);

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MyDelegate.cpp

QWidget *MyDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    if(index.column() == 0)
        return new CustomWidget(parent);
    if(index.column() == 1)
        return new QComboBox(parent);
 
}

QWidget *MyDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    if(index.column() == 0)
        return new CustomWidget(parent);
    if(index.column() == 1)
        return new QComboBox(parent);

}

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CustomWidget.cpp

CustomWidget::CustomWidget(QWidget *parent) : QWidget(parent)
{
QLineEdit *edit = new QLineEdit;
QPushButton *but = new QPushButton;
QHBoxLayout *layout = new QHBoxLayout;
layout->addWidget(edit);
layout->addWidget(but);
setLayout(layout);
}

CustomWidget::CustomWidget(QWidget *parent) : QWidget(parent)
{
QLineEdit *edit = new QLineEdit;
QPushButton *but = new QPushButton;
QHBoxLayout *layout = new QHBoxLayout;
layout->addWidget(edit);
layout->addWidget(but);
setLayout(layout);
}

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