{{notability|date=August 2014}}
In computer programming, a '''window class''' is a fundamental in many windowing systems, including the Microsoft Windows (Win16, Win32, and Win64) operating systems, IBM OS/2<ref name=Petzold /> and the X Window System.<ref>{{cite book |author1=Pavlidis, Theo |article=WINDOW SYSTEMS |title=Wiley Encyclopedia of Electrical and Electronic Engineering (draft) |url=https://www3.cs.stonybrook.edu/~theo/winsys.html}}</ref> The class defines the window procedure used to process messages for all windows created with that class.<ref name="Petzold">{{cite book |last1=Petzold |first1=Charles |title=Programming The OS/2 Presentation Manager |date=1989 |publisher=Microsoft Press |isbn=1-55615-170-5 |url=https://komh.github.io/os2books/txt/ppm.txt}}</ref>
The structure provides a template from which windows may be created by specifying a window's icons, menu, background color and a few other features. It also holds a pointer to a procedure that controls how the window behaves in response to user interaction. It finally tells the operating system how much additional storage space is needed for the class and each window created from it.
==References== <references />
==External links== *[http://msdn2.microsoft.com/en-us/library/ms633576.aspx A manual page for window class on Microsoft's website] *[http://msdn.microsoft.com/en-us/library/ms633574(VS.85).aspx About Window Classes]
Category:Microsoft application programming interfaces
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