Problem resizing a QFrame

[rawfool]

I've created a window and added a frame to it. The frame would contain some widgets such as LineEdit, ListBox, etc. I would change one frame with another one according to a menu selection. Now my issue is, when I maximize the main window, the frame is not getting expanded according to the new size. I tried to look at a few functions like sizePolicy, etc, but didn't understand though. I've provided the code below.

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QtGui/QMainWindow>
#include <QVBoxLayout>
#include <QFrame>
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();
    void baseLayerSettings(void);
 
private:
    QFrame *baseLayer;
 
};
 
#endif // MAINWINDOW_H

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QtGui/QMainWindow>
#include <QVBoxLayout>
#include <QFrame>

class MainWindow : public QMainWindow
{
    Q_OBJECT

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

private:
    QFrame *baseLayer;

};

#endif // MAINWINDOW_H

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mainwindow.cpp

#include "mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    baseLayerSettings();
}
 
MainWindow::~MainWindow()
{
 
}
void MainWindow::baseLayerSettings(void)
{
    baseLayer = new QFrame(this);
    baseLayer->setGeometry(0, 0, 800, 600);
    baseLayer->setFrameStyle(QFrame::StyledPanel | QFrame::Plain);
    baseLayer->setStyleSheet("background-color: qlineargradient(spread:pad, x1:0.504, y1:1, x2:0.497273, y2:0, stop:0 rgba(51, 142, 220, 255), stop:1 rgba(255, 255, 255, 255))");
 
}

#include "mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    baseLayerSettings();
}

MainWindow::~MainWindow()
{

}
void MainWindow::baseLayerSettings(void)
{
    baseLayer = new QFrame(this);
    baseLayer->setGeometry(0, 0, 800, 600);
    baseLayer->setFrameStyle(QFrame::StyledPanel | QFrame::Plain);
    baseLayer->setStyleSheet("background-color: qlineargradient(spread:pad, x1:0.504, y1:1, x2:0.497273, y2:0, stop:0 rgba(51, 142, 220, 255), stop:1 rgba(255, 255, 255, 255))");
 
}

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Please help me with this. Thank you.

[norobro]

. . . added a frame to it. . . .

No, you haven't. Try this:

baseLayerSettings();
setCentralWidget(baseLayer);

baseLayerSettings();
setCentralWidget(baseLayer);

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[rawfool]

Thank you dude. It worked.