>>>However, for some reason I could not figure out how to add DevExpress controls. I found them in Windows\Assembly, but I can not add them from there.
>>
>>Why can't you add them?
>
>May be because it's the Assembly file and the dialog looks for dll/exe files?

Have not done this myself, but

[If you have compiled the class]

There's a browse button, it will pick up your dll/exe