Qt missing application's icon in Windows' bottom bar

[A Former User]

Welcome, I have a question about Qt's windows operations. I have a simple app which contains 2 windows:

MainWindow - includes push button, can't be resizeable,
AdminWindow - includes label, can be resizeable.
When I click push button, it should open AdminWindow and hide MainWindow. I made the app and it seems to work but when I open the AdminWindow, the application icon which is located in windows's bottom bar is missing. How can I fix it?

Icon is showed in bottom bar:

Icon isn't showed in bottom bar:

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "adminwindow.h"

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private slots:
    void on_pushButtonOpenAdmin_clicked();

private:
    Ui::MainWindow *ui;
    AdminWindow *adminWindow;
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}

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

// hides MainWindow and show AdminWindow
void MainWindow::on_pushButtonOpenAdmin_clicked()
{
    hide();
    adminWindow = new AdminWindow(this);
    adminWindow->show();
}

adminwindow.h

#ifndef ADMINWINDOW_H
#define ADMINWINDOW_H

#include <QMainWindow>

namespace Ui {
class AdminWindow;
}

class AdminWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit AdminWindow(QWidget *parent = 0);
    ~AdminWindow();

private:
    Ui::AdminWindow *ui;
};

#endif // ADMINWINDOW_H

adminwindow.cpp

#include "adminwindow.h"
#include "ui_adminwindow.h"

AdminWindow::AdminWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::AdminWindow)
{
    ui->setupUi(this);
}

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

[dheerendra]

Try not passing this as parent while creating adminwindow

[A Former User]

@dheerendra Yes, it works! Thank you very much, you're great.

[dheerendra]

Move the Qn to solved state. This helps others as well