[Seaside] Navigate to component via anchor?

[Ramon Leon]

> 
> Okay, I figured call isn't the right thing to do because the 
> call'ed component will retain control until it answers. Fair 
> enough. Now I'm back to the idea of setting the 'menu' 
> variable on the 'component' so that components could ask the 
> menu to do the navigation for them. Ouch! Somebody tell me 
> there's a better way to do this, its not immediately obvious 
> to me what to do here...
> 
> Thanks!
> 
> -Boris

Small hint... You don't always have to say "self call:", you can say
"mainArea call:", and only that area will be replaced by the called
component.