The CopyLocal parameter of the references to the DevExpress.* assemblies should be set to False. There is a problem in that Visual Studio .NET cannot locate the DevExpress.~ designer assemblies in this case. We don't know how to overcome this issue. You may try to copy the DevExpress.*.Design assemblies to the Bin directory of your project. However, you cannot distribute them with your application according to EULA.
Here is the screenshot illustrating how to check the CopyLocal property's value:
Troubleshooting design-time problems
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How to fix the NullReferenceException when creating a component by dragging its icon from the Toolbox
How to obtain a design-time exception call stack
How to resolve the design-time problem when opening forms in Visual Studio 2005 after updating DevExpress controls