Desktop Developer, "Develop Composite Controls," by Douglas Gennetten and Jonathan Lurie
Visual Studio Magazine
February 2003

For this solution to run you need to have Visual Studio.NET
You can open CollapsingPanelControl.sln, the solution has two projects:

CollapsingControls.csproj
TestApp.csproj

The TestApp has a project reference to CollapsingControls and should be set as the StartUp Project.  
Open Form1.cs to see work with the Controls in design time.
