A library for developing Windows® applications and UI components. Extends ATL (Active Template Library) and provides a set of classes for controls, dialogs, frame windows, GDI objects, and more. This version provides full support for Visual Studio .NET and Windows XP.

WTL provides support for implementing various user interface elements, from frame and popup windows, to MDI, standard and common controls, common dialogs, property sheets and pages, GDI objects, UI updating, scrollable windows, splitter windows, command bars, etc. The WTL classes are mostly templated and use minimal instance data and inline functions. They were not designed as a framework, so they do not impose a particular application model, and can accommodate any. The classes do not use hooks or thread local storage, so they have no restrictions that those techniques impose. They also have no inter-dependencies and can be freely mixed with straight SDK code. In summary, WTL delivers very small and efficient code, very close in size and speed to SDK programs, while presenting a more logical, object oriented model to a programmer.