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.

I can understand "why" but its still a bit annoying! I have some windows forms user controls that inherit from a class that implements generics. Problem is the designer can't reflect those classes and in turn spits out the wonderful error above.

The work around I am using only covers base classes that do not inherit visually (though I have not tried otherwise). Basically when I want to edit the control visually I do this:

public partial class DerivedControl
//: UserControl
: GenericControlBase<XyzEntity>
{...}

And when I am done, I flick it back:

public partial class DerivedControl
: UserControl
//: GenericControlBase<XyzEntity>
{...}

Tis a hack, but it works!

 

---

BTW, I applied the patch mentioned earlier - http://support.microsoft.com/default.aspx?scid=kb;en-us;912019 - and my designer issues went away (except for the generics stuff but that’s cool). I did experience problems with vanilla controls, but not vanilla forms... I did find that the only real fix when it does happen was to close VS.Net and re-open. I also noticed that if forms were open when the project was loaded the issue was more likely to come up.