Why don't my widgets get displayed?

I am trying to create layout like this

In the QT i created widgets and put in the main widget, the problem is not visible. none of the widget's are not shown. please help me to fix this issue

Complete Source Code sandbox.ifuturemec.com/test.zip

Source code mainWindow.cpp

#include "mainwindow.h"
#include <QtGui>
#include "headerbar.h"
#include <QGridLayout>
#include <QPushButton>
#include <QBoxLayout>
#include "statusbar.h"
#include "leftpanel.h"
#include "rightpanel.h"
#include "centerpanel.h"

mainWindow::mainWindow(QWidget *parent) : QWidget(parent)
{
   QGridLayout *layout=new QGridLayout(this);

    headerBar *Header= new headerBar(this);
    leftPanel *LeftPanel=new leftPanel(this);
    centerPanel *CenterPanel=new centerPanel(this);
    rightPanel *RightPanel=new rightPanel(this);
    statusBar *Status=new statusBar(this);

    QHBoxLayout *box=new QHBoxLayout();
    box->addWidget(LeftPanel);
    box->addWidget(CenterPanel);
    box->addWidget(RightPanel);

    layout->addWidget(Header,0,0);
    layout->addLayout(box,1,0);
    layout->addWidget(Status,2,0);

    setLayout(layout);
}

mainWindow::~mainWindow() {}

mainWindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QWidget>

class mainWindow : public QWidget
{
    Q_OBJECT
public:
    mainWindow(QWidget *parent = 0);
    ~mainWindow();

signals:

public slots:

};

#endif // MAINWINDOW_H

headerbar.cpp

#include "headerbar.h"
#include <QPushButton>
#include <QMessageBox>

headerBar::headerBar(QWidget *parent) : QWidget(parent)
{
    this->setMaximumHeight(24);
    this->setStyleSh开发者_C百科eet("background-color: rgb(85, 170, 255)");
}

headerBar::~headerBar(){}

headerbar.h

#ifndef HEADERBAR_H
#define HEADERBAR_H

#include <QWidget>

class headerBar : public QWidget
{
    Q_OBJECT
public:
    headerBar(QWidget *parent = 0);
    ~headerBar();

signals:

public slots:

};

#endif // HEADERBAR_H

Please help me to fix this problem.

Actually, your widgets do show ! But they are empty and have nothing to show !

Regarding the background color you are setting : the background-color property is not showing, because this property is not supported by QWidget.

Have a look at the documentation regarding this : List of stylable widgets.

More specifically :

QWidget : Supports only the background, background-clip and background-origin properties.

If you try to put, for instance, a label in your widgets, you'll see they do show :

centerPanel::centerPanel(QWidget *parent) :
    QWidget(parent)
{
    QHBoxLayout *box = new QHBoxLayout(this);
    QLabel* pLabel = new QLabel("Center panel", this);
    box->addWidget(pLabel);
    this->setStyleSheet("background-color: rgb(85, 100, 100)");
}

If you just want the mainWindow to have a solid background color, you might try to just forget using the stylesheet and override the paintEvent method like this:

void mainWindow::paintEvent(QPaintEvent *event)
{
setPalette(QPalette(QColor(85, 170, 255)));
setAutoFillBackground(true); 
}