WPF Input and Commands Patterns

Handling user input and implementing command patterns in WPF applications.

1. Command System Overview

ICommand (Interface)
├── RoutedCommand (WPF built-in)
│   ├── ApplicationCommands (Copy, Paste, Cut, etc.)
│   ├── NavigationCommands (BrowseBack, BrowseForward, etc.)
│   ├── MediaCommands (Play, Pause, Stop, etc.)
│   └── EditingCommands (ToggleBold, ToggleItalic, etc.)
└── RelayCommand / DelegateCommand (MVVM)

2. Built-in Commands