To connect principal window with a second one

[Stanfillirenfro]

Greetings to all of you!
I am facing a problem of connecting a parent window with a children one. I have successfully implemented each window as well as their respectives widgets, but the slots of the children window does not work.
Here is my code:

#ifndef DEF_ESSAIE
#define DEF_ESSAIE
 
#include <QtGui>
 
class Essaie: public QMainWindow
{
    Q_OBJECT
 
public:
    Essaie();
    ~Essaie();
 
private slots:
    void ouvrirFenetre1();
 
 
private:
    QMainWindow *m_fenetrePrincipale;
    QPushButton *m_butonFenetre1;
 
};
#endif // ESSAIE_H

#ifndef DEF_ESSAIE
#define DEF_ESSAIE

#include <QtGui>

class Essaie: public QMainWindow
{
    Q_OBJECT

public:
    Essaie();
    ~Essaie();

private slots:
    void ouvrirFenetre1();


private:
    QMainWindow *m_fenetrePrincipale;
    QPushButton *m_butonFenetre1;

};
#endif // ESSAIE_H

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#ifndef DEF_FENETRE1
#define DEF_FENETRE1
 
#include<QtGui>
 
class Fenetre1: public QMainWindow
{
    Q_OBJECT
 
public:
    Fenetre1(QWidget *parent);
    ~Fenetre1();
 
private slots:
 
void displayList();
 
private:
    QWidget *m_fenetre1;
    QPushButton *m_butonFermer;
 
};
#endif // FENETRE1_H

#ifndef DEF_FENETRE1
#define DEF_FENETRE1

#include<QtGui>

class Fenetre1: public QMainWindow
{
    Q_OBJECT

public:
    Fenetre1(QWidget *parent);
    ~Fenetre1();

private slots:

void displayList();

private:
    QWidget *m_fenetre1;
    QPushButton *m_butonFermer;

};
#endif // FENETRE1_H

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#include "Essaie.h"
#include "Fenetre1.h"
 
 
Essaie::Essaie()
{
    m_fenetrePrincipale = new QMainWindow;
    m_fenetrePrincipale->setFixedSize(300, 200);
 
 
    m_butonFenetre1 = new QPushButton("Ouvrir", this);
    m_butonFenetre1->move(75, 100);
 
 
    connect(m_butonFenetre1, SIGNAL(clicked()), this, SLOT(ouvrirFenetre1()));
 
}
 
void Essaie::ouvrirFenetre1()
{
    Fenetre1 *fene = new Fenetre1(this);
    fene->show();
 
}
 
Essaie::~Essaie()
{}

#include "Essaie.h"
#include "Fenetre1.h"


Essaie::Essaie()
{
    m_fenetrePrincipale = new QMainWindow;
    m_fenetrePrincipale->setFixedSize(300, 200);


    m_butonFenetre1 = new QPushButton("Ouvrir", this);
    m_butonFenetre1->move(75, 100);


    connect(m_butonFenetre1, SIGNAL(clicked()), this, SLOT(ouvrirFenetre1()));

}

void Essaie::ouvrirFenetre1()
{
    Fenetre1 *fene = new Fenetre1(this);
    fene->show();

}

Essaie::~Essaie()
{}

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#include "Fenetre1.h"
 
Fenetre1::Fenetre1(QWidget *parent = 0): QMainWindow(parent)
{
    this->setFixedSize(200, 150);
    this->setWindowTitle("Fenetre1");
 
    m_butonFermer = new QPushButton("Fermer", this);
 
    connect(m_butonFermer, SIGNAL(clicked()), this, SLOT(close()));
    connect(m_butonDisplay, SIGNAL(clicked()), this, SLOT(displayList()));
 
}
 
Fenetre1::~Fenetre1()
{}

#include "Fenetre1.h"

Fenetre1::Fenetre1(QWidget *parent = 0): QMainWindow(parent)
{
    this->setFixedSize(200, 150);
    this->setWindowTitle("Fenetre1");

    m_butonFermer = new QPushButton("Fermer", this);
   
    connect(m_butonFermer, SIGNAL(clicked()), this, SLOT(close()));
    connect(m_butonDisplay, SIGNAL(clicked()), this, SLOT(displayList()));

}

Fenetre1::~Fenetre1()
{}

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On the children window, the closing slot is working properly, but not that of display.
I would be greatfull to you if you could help me overcoming this problem.
Many thanks in advance!