I've a MediaPanel which inherits from QWidget and I want to hide the title bar but event if I set the flags with setWindowFlags(Qt::CustomizeWindowHint | Qt::WindowTitleHint); (or some other flags like ) the result is still the same :

and if I use setWindowFlags(Qt::Window | Qt::FramelessWindowHint); I lose all the buttons, labels and sliders :

I've played with the Qt example and some combination seems to be impossible...

EDIT :

I've posted a reduced part of my code, could someone tell me where should I set the flags ?

main.cpp :

#include <QApplication>
#include "JokerWindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    JokerWindow w(&settings);
    w.show();
    return a.exec();
}

JokerWindow.h

#ifndef JOKERWINDOW_H
#define JOKERWINDOW_H

#include <QMainWindow>
#include "PhCommonUI/PhMediaPanelDialog.h"

namespace Ui {
class JokerWindow;
}

class JokerWindow : public QMainWindow
{
    Q_OBJECT
public:
    explicit JokerWindow(QSettings *settings);
    ~JokerWindow();

private:
    PhMediaPanelDialog _mediaPanel;
};
#endif // MAINWINDOW_H

JokerWindow.cpp

#include "JokerWindow.h"
#include "ui_JokerWindow.h"

JokerWindow::JokerWindow(QSettings *settings) :
    QMainWindow(NULL),
    ui(new Ui::JokerWindow)
{
    _mediaPanel.show();
}
JokerWindow::~JokerWindow()
{
    delete ui;
}

PhMediaPanel.h

#ifndef PHMEDIAPANEL_H
#define PHMEDIAPANEL_H

#include <QWidget>
namespace Ui {
    class PhMediaPanel;
}
class PhMediaPanel : public QWidget
{
    Q_OBJECT
public:
    explicit PhMediaPanel(QWidget *parent = 0);
    ~PhMediaPanel();
private:
    Ui::PhMediaPanel *ui;
};

#endif // PHMEDIAPANEL_H

PhMediaPanel.cpp

#include "PhMediaPanel.h"
#include "ui_PhMediaPanel.h"
PhMediaPanel::PhMediaPanel(QWidget *parent) :
    QWidget(parent)
{
    ui->setupUi(this);
}
PhMediaPanel::~PhMediaPanel()
{
    delete ui;
}