小改

SoftwareDesign/Code/2-2-5_enhanced/mainwindow.ui

@@ -60,7 +60,7 @@
     <item row="1" column="0">
      <widget class="QPushButton" name="clearBtn">
       <property name="text">
-       <string>Clear</string>
+       <string>Back</string>
       </property>
      </widget>
     </item>

SoftwareDesign/Code/2-3-3/mainwindow.ui

@@ -11,7 +11,7 @@
    </rect>
   </property>
   <property name="windowTitle">
-   <string>MainWindow</string>
+   <string>4490</string>
   </property>
   <widget class="QWidget" name="centralwidget">
    <widget class="QLabel" name="label">

SoftwareDesign/Code/2-3-4/2-3-4.pro

@@ -0,0 +1,24 @@
+QT       += core gui
+
+greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
+
+CONFIG += c++17
+
+# You can make your code fail to compile if it uses deprecated APIs.
+# In order to do so, uncomment the following line.
+#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
+
+SOURCES += \
+    main.cpp \
+    mainwindow.cpp
+
+HEADERS += \
+    mainwindow.h
+
+FORMS += \
+    mainwindow.ui
+
+# Default rules for deployment.
+qnx: target.path = /tmp/$${TARGET}/bin
+else: unix:!android: target.path = /opt/$${TARGET}/bin
+!isEmpty(target.path): INSTALLS += target

SoftwareDesign/Code/2-3-4/main.cpp

@@ -0,0 +1,11 @@
+#include "mainwindow.h"
+
+#include <QApplication>
+
+int main(int argc, char *argv[])
+{
+    QApplication a(argc, argv);
+    MainWindow w;
+    w.show();
+    return a.exec();
+}

SoftwareDesign/Code/2-3-4/mainwindow.cpp

@@ -0,0 +1,15 @@
+#include "mainwindow.h"
+#include "ui_mainwindow.h"
+
+MainWindow::MainWindow(QWidget *parent)
+    : QMainWindow(parent)
+    , ui(new Ui::MainWindow)
+{
+    ui->setupUi(this);
+}
+
+MainWindow::~MainWindow()
+{
+    delete ui;
+}
+

SoftwareDesign/Code/2-3-4/mainwindow.h

@@ -0,0 +1,27 @@
+#ifndef MAINWINDOW_H
+#define MAINWINDOW_H
+
+#include <QMainWindow>
+#include <QWheelEvent>
+#include <QMouseEvent>
+
+QT_BEGIN_NAMESPACE
+namespace Ui {
+class MainWindow;
+}
+QT_END_NAMESPACE
+
+class MainWindow : public QMainWindow {
+  Q_OBJECT
+
+public:
+  MainWindow(QWidget *parent = nullptr);
+  ~MainWindow();
+
+private:
+  Ui::MainWindow *ui;
+
+protected:
+  void mouseEvent(QMouseEvent *e);
+};
+#endif // MAINWINDOW_H

SoftwareDesign/Code/2-3-4/mainwindow.ui

@@ -0,0 +1,58 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<ui version="4.0">
+ <class>MainWindow</class>
+ <widget class="QMainWindow" name="MainWindow">
+  <property name="geometry">
+   <rect>
+    <x>0</x>
+    <y>0</y>
+    <width>800</width>
+    <height>600</height>
+   </rect>
+  </property>
+  <property name="windowTitle">
+   <string>4490</string>
+  </property>
+  <widget class="QWidget" name="centralwidget">
+   <widget class="QLabel" name="label">
+    <property name="geometry">
+     <rect>
+      <x>110</x>
+      <y>160</y>
+      <width>77</width>
+      <height>25</height>
+     </rect>
+    </property>
+    <property name="text">
+     <string>TextLabel</string>
+    </property>
+   </widget>
+   <widget class="QLabel" name="label_2">
+    <property name="geometry">
+     <rect>
+      <x>330</x>
+      <y>160</y>
+      <width>77</width>
+      <height>25</height>
+     </rect>
+    </property>
+    <property name="text">
+     <string>TextLabel</string>
+    </property>
+   </widget>
+  </widget>
+  <widget class="QMenuBar" name="menubar">
+   <property name="geometry">
+    <rect>
+     <x>0</x>
+     <y>0</y>
+     <width>800</width>
+     <height>30</height>
+    </rect>
+   </property>
+  </widget>
+  <widget class="QStatusBar" name="statusbar"/>
+ </widget>
+ <resources/>
+ <connections/>
+</ui>