### 3. Dark Mode Detection

def is_dark_mode():
    if sys.platform == "darwin":
        # MacOS dark mode detection
        process = subprocess.Popen(
            ["defaults", "read", "-g", "AppleInterfaceStyle"],
            stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        out, _ = process.communicate()
        return out.strip() == b"Dark"
    elif sys.platform == "win32":
        # Windows 10+ dark mode detection
        try:
            import winreg
            key = winreg.OpenKey(
                winreg.HKEY_CURRENT_USER,
                r"Software\Microsoft\Windows\CurrentVersion\Themes\Personalize")
            value, _ = winreg.QueryValueEx(key, "AppsUseLightTheme")
            return value == 0
        except:
            return False
    else:
        return False  # Default to light mode on other platforms

---

## 🔹 Practical Example: Plugin-Based Text Editor

class TextEditor(QMainWindow):
    def __init__(self):
        super().__init__()
        self.plugins = []
        self.setup_ui()
        self.load_plugins()
    
    def setup_ui(self):
        # Core editor
        self.editor = QPlainTextEdit()
        self.setCentralWidget(self.editor)
        
        # Plugin toolbar
        self.plugin_toolbar = QToolBar("Plugins")
        self.addToolBar(Qt.LeftToolBarArea, self.plugin_toolbar)
        
        # Plugin menu
        self.plugin_menu = self.menuBar().addMenu("Plugins")
    
    def load_plugins(self):
        plugin_dir = os.path.join(os.path.dirname(__file__), "plugins")
        if not os.path.exists(plugin_dir):
            return
            
        for filename in os.listdir(plugin_dir):
            if filename.endswith('.py'):
                try:
                    spec = importlib.util.spec_from_file_location(
                        f"plugins.{filename[:-3]}", 
                        os.path.join(plugin_dir, filename))
                    module = importlib.util.module_from_spec(spec)
                    spec.loader.exec_module(module)
                    
                    for name, obj in inspect.getmembers(module):
                        if (inspect.isclass(obj) and 
                            issubclass(obj, BasePlugin) and 
                            obj != BasePlugin):
                            plugin = obj(self)
                            plugin.initialize()
                            self.plugins.append(plugin)
                            
                            # Add to UI
                            if hasattr(plugin, 'get_toolbar_widget'):
                                self.plugin_toolbar.addWidget(
                                    plugin.get_toolbar_widget())
                            if hasattr(plugin, 'get_menu_action'):
                                self.plugin_menu.addAction(
                                    plugin.get_menu_action())
                except Exception as e:
                    print(f"Failed to load plugin {filename}: {e}")

class BasePlugin:
    def __init__(self, editor):
        self.editor = editor
        
    def initialize(self):
        raise NotImplementedError

---

## 🔹 Best Practices for Production Apps
1. Error Handling
- Implement comprehensive logging
- Use sentry.io for crash reporting
- Create recovery mechanisms

2. Update Strategy
- Implement delta updates
- Support rollback capability
- Verify digital signatures

3. Accessibility
- Set proper widget roles
- Support screen readers
- Ensure keyboard navigation

4. Security
- Sanitize all inputs
- Use HTTPS for network requests
- Secure sensitive data storage

5. Testing
- Unit tests for core logic
- UI tests with QTest
- Cross-platform testing matrix

---

### 🎉 Congratulations on Completing the Series!
You've now mastered:
1. PyQt5 Fundamentals
2. Advanced Widgets & Customization
3. Database Integration & MVC
4. Networking & Multimedia
5. Internationalization & Deployment
6. Advanced Architecture & Optimization

#PyQt5Mastery #ProfessionalGUI #PythonDevelopment 🚀