WindowsBase

WindowsBase is a core .NET assembly (WindowsBase.dll) that provides foundational types and services used by Windows Presentation Foundation (WPF) and other Windows-based components. It is part of the .NET Framework and, in modern runtimes, part of the shared framework. WindowsBase supplies the low-level infrastructure upon which higher-level WPF features build, including the property system, event routing, and threading model.

Representative types and concepts provided by WindowsBase include:

- DependencyObject and DependencyProperty: the core of the WPF property system, enabling runtime property value resolution and change notification.

- RoutedEvent and routing infrastructure: support for event tunneling and bubbling within the visual tree.

- Dispatcher and DispatcherObject: threading model for WPF UI components, ensuring operations occur on the UI thread.

- Freezable: a base class for objects that can become immutable to improve performance and sharing of resources.

WindowsBase is typically referenced by WPF applications and many UI components use it indirectly. It is distributed with the framework and has evolved across .NET Framework, .NET Core, and .NET 5+/6+. It is not a UI element by itself but rather a backbone for WPF runtime services. See also, Windows Presentation Foundation, DependencyProperty, RoutedEvent, Dispatcher, and Freezable.