This is an example of a library. You may see a list of other libraries used on Rosetta Code at Category:Solutions by Library.
WPK is a PowerShell module that enables the use of WPF for creating graphical user interfaces. WPF is usually used through XAML markup, WPK wraps creation of windows and controls in own cmdlets that can be nested. Event handlers can be attached simply by including another parameter. For the most part this results in code that's readable and compact. It also lends itself to quick prototyping much better than Windows Forms.