This is just to share a question posed by customer Ilan, and the resolution he found; regarding the proper location of dll's required by the CAB Extensibility Kit:

Question: I've compiled the CAB Extensibility Kit and wanted to add the items (Workspaces etc.) to the toolbox in VS2008.  i chose "add item" on a new tab in the toolbox and tried to browse and point at the "C:\Documents and Settings\All Users\Documents\Infragistics\NetAdvantage for .NET 2008 Vol. 2 CLR 2.0\CAB Extensibility Kit\Source\Infragistics.CompositeUI.WinForms\bin\Debug\Infragistics.Practices.CompositeUI.WinForms.dll". However I'm getting a message box saying: "There was an error loading types from assembly 'C:\Documents and Settings\All Users\Documents\Infragistics\NetAdvantage for .NET 2008 Vol. 2 CLR 2.0\CAB Extensibility Kit\Source\Infragistics.CompositeUI.WinForms\bin\Debug\Infragistics.Practices.CompositeUI.WinForms.dll' 'Could not load file or assembly 'Microsoft.Practices.CompositeUI, version=1.0.51205.0, Culture=neutral, PublicKey Token=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.'" Can you please tell me what did I do wrong?

Thanks for your help, Ilan.

My suggestion:
I would like to ask if you can find the following files in C:\Documents and Settings\All Users\Documents\Infragistics\NetAdvantage for .NET 2008 Vol. 2 CLR 2.0\CAB Extensibility Kit\Source\Infragistics.CompositeUI.WinForms\bin\Debug:

Microsoft.Practices.CompositeUI.dll
Microsoft.Practices.CompositeUI.WinForms.dll
Microsoft.Practices.ObjectBuilder.dll

If the above listed files are not present, then you may need to navigate upwards four levels and compile the solution: C:\Documents and Settings\All Users\Documents\Infragistics\NetAdvantage for .NET 2008 Vol. 2 CLR 2.0\CAB Extensibility Kit\Infragistics.CompositeUI.WinForms.sln.

Ilan's resolution:
I worked some more after your clue, and what solved it was the delete the Microsoft.Practices.CompositeUI, Microsoft.Practices.CompositeUI.WinForms, Microsoft.Practices.ObjectBuilder, and re-add them again from c:\Program Files\Microsoft Composite UI App Block\CSharp\Source\CompositeUI.WinForms\bin\Debug

Suddenly i was able to add the Infragistics.CompositeUI.WinForms and they all appeared in the toolbox: ImageSmartPartInfo, UltraMdiTabWorkspace, UltraExplorerBarWorkspace, UltraMdiTabSmartPartInfo, UltraDockWorkspace, UltraExplorerBarSmartPartInfo, UltraTabWorkspace, UltraToolbarsSmartPartInfo, UltraToolbarsManagerWorkspace, UltraTabSmartPartInfo and UltraDockSmartPartInfo...