Microsoft on Tuesday night released the source code for its Windows Template Library under the open-source Common Public License and posted it on SourceForge, the open-source code repository. The Windows Template Library (WTL) is a library for developing Windows applications and user interface components. It also extends the Active Template Library (ATL) and provides a set of classes for controls, dialogs, frame windows, GDI objects and more.
The ATL is a set of template classes developed by Microsoft Corp. to aid in the development of ActiveX controls and Component Object Model (COM) objects. They"re template-based C++ classes that simplify the programming of COM objects. The COM support in Visual C++ allows developers to easily create a variety of COM objects, Automation servers and ActiveX controls.