Symptoms 

Consultingwerk.SmartComponents.Base.SmartViewerControl causing complie erorrs:

Multiple markers at this line - ** C:\Users\cvb\git\smartcomponentlibrary_nofw_utf8\Consultingwerk

\SmartComponents\Base\SmartViewerControl.cls Could not understand line 464. (196) - Invalid datatype

 specified: Consultingwerk.SmartComponents.Interfaces.Design.IDesignDataSource. Specify a datatype such as

 'character' or the name of a class. (5638)

Cause

Customer was editing the SmartViewerControl.cls file while debugging a potential issue. While editing the class file, the editor has reordered the USING Statements of the class resulting in the compile error above. 

Solution

Reset modified SmartComponent Library source code to match exactly the version tested and shipped by Consultingwerk.