QPushButton is not showing on QTableView (QItemDelegate procedure used)

I have a QTableView of 4 rows and 4 columns. I am trying to add a QPushButton to all cells of the last column only, with the exception of the first row. When I run my code I am able to see the table but when I click on each cell of the 4 column I see the QPushButton but it disappears instantly. Only the word "Detail" on the QPushButton remains visible. And I still see the QPushButton on the first row. Any ideas?

This is the buttoncolumndelegate.cpp

#include "buttoncolumndelegate.h"

ButtonColumnDelegate::ButtonColumnDelegate(QObject *parent) :
    QItemDelegate(parent)
{

}
QWidget * ButtonColumnDelegate::createEditor(QWidget *parent,
            const QStyleOptionViewItem &option,
            const QModelIndex &index) const
{
    QPushButton *detail = new QPushButton("Detail",parent);
    detail->setText("Detail");
    (void) option;
    (void) index;
    return detail;
}

void ButtonColumnDelegate::setEditorData(QWidget *editor,
                                     const QModelIndex &index) const
{
    QPushButton *detail = qobject_cast<QPushButton *>(editor);
    detail->setProperty("Detail", "Detail");
    detail->setText("Detail");
    (void) index;
}

void ButtonColumnDelegate::setModelData(QWidget *editor, QAbstractItemModel *model,
                                    const QModelIndex &index) const
{
    QPushButton *detail = qobject_cast<QPushButton *>(editor);
    model->setData(index, detail->property("Detail"));

}

void ButtonColumnDelegate::updateEditorGeometry(QWidget *editor,
                              const QStyleOptionViewItem &option,
                              const QModelIndex &index) const
{
    editor->setGeometry(option.rect);
    (void) index;  

This is the dialog.cpp

#include "dialog.h"
#include "ui_dialog.h"
#include "buttoncolumndelegate.h"

Dialog::Dialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::Dialog)
{
    ui->setupUi(this);

    mybutton = new ButtonColumnDelegate(this);
    mModel = new QStandardItemModel(4,4,this);
    ui->tableView->setModel(mModel);
    ui->tableView->setItemDelegateForColumn(3, mybutton);

}

Dialog::~Dialog()
{
    delete ui;
}                     

createEditor() is called only when you want to edit a widget, instead if you want a button to be displayed when you are not editing a value you must overwrite the paint() method

void ButtonColumnDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{
    QPushButton button(index.data().toString());
    button.setGeometry(option.rect);
    painter->save();
    painter->translate(option.rect.topLeft());
    button.render(painter);
    painter->restore();
}