Hello,
i dont know if its realy is a bug:
if ur creating a panel with a builder or an other element u can set controller(MyController controller).
but the controller u set isn´t used, instead a new one of class MyController is created.
if its not a bug i would change the parameter type to [java]controller(Class<? extends Controller> theClass)[/java] or
[java]controller(Class<Controller> theClass)[/java]
It’s not a bug but it’s not intuitive. I agree 
Would you please be so kind and add this as a feature request to the official Nifty tracker at sourceforge.net? Thank you!