QT5 Widgets 大小切换问题

Question

I try to switch between two different Widgets in QT5. The first problem was that my first window was visible in the background of my second window. I solve this with a check in "autoFillBackground". Now i can switch between them, but if i resize them it only resize the Main content.

Both Widgets have a grid layout.

Resize Problem

Im new at QT5, so is there a better way to make a switching between 2 widgets without this problem?

I try it with wMessages = new Messages(); and hide() but then my program crash after going back.

---

Code:

mainwindow.h:

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

#include "messages.h"

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_btnMessages_clicked();

private:
    Ui::MainWindow *ui;
    Messages *wMessages;
};
#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;
}

void MainWindow::on_btnMessages_clicked()
{
    wMessages = new Messages(this); 
    wMessages->show();
}

messages.h:

#ifndef MESSAGES_H
#define MESSAGES_H

#include <QWidget>

namespace Ui {
class Messages;
}

class Messages : public QWidget
{
    Q_OBJECT

public:
    explicit Messages(QWidget *parent = nullptr);
    ~Messages();

    QString NewsGenerator();
private slots:
    void on_bBack_clicked();

    void on_pushButton_clicked();

private:
    Ui::Messages *ui;
};

#endif // MESSAGES_H

messages.cpp:

#include "messages.h"
#include "ui_messages.h"

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

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

void Messages::on_bBack_clicked()
{
    this->close();
    QWidget *parent = this->parentWidget();
    parent->show();
}

---

Edit 1 - working Main Window Button (from GM´s answer):

void MainWindow::on_btnMessages_clicked()
{
    wPlaner = new Planer();
    QMainWindow::setCentralWidget(wPlaner);
}

Answer 1

Update (based on the comments):

The best solution was to use the QStackedWidget to navigate between the views.

Docu: https://doc.qt.io/qt-5/qstackedwidget.html#details

---

Example-Code for Button:

// return back to first view
void MainWindow::on_btnret_clicked()
{
    ui->stackedWidget->setCurrentIndex(0);
}