I was thinking I could use this to set layouts & return types to the
event by looking at URL values
The requestContextDecorator would see these come in, make sure the
data is valid and set the values to prc, so in controllers I could
just event.setView(name='foo',nolayout=prc.nolayout) and the same idea
with renderData

But anything passed to an event never gets to the
requestContextDecorator, getRequestContext().getCollection() dont have
access to url/form keys. Does Configure() run before it can get that
information? Is there a way to do this?

And, of course just minutes later.
Came across Aaron's blog, about something else, which lead me to use
an interceptor instead of the RCD, since this seems to be the way to
do it.