.NET Questions - Designer can't be shown - classes can't be designed

.NET Questions - Designer can't be shown - classes can't be designed: "I had a similar problem but I was inheriting from a generic base class... This was the kind of error I was getting:

'The designer could not be shown for this file because none of the classes within it can be designed. The designer inspected the following classes in the file: DerivedControl --- The base class 'GenericControlBase' could not be loaded. Ensure the assembly has been referenced and that all projects have been built.'"


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solution is to close all forms