[Seaside] Completelly pharo hang with seaside3

[David Carlos Manuelda]

In some of my examples, I subclassed WAComponent in order to test things 
further.

I discovered that if you implement on class side the method name with self 
subclassResponsibility, then, pharo completelly hangs.

Maybe is not a bug and is something I should not be doing, but anyways, it 
is not worth to hang pharo completelly, can it be reviewed?

It can be tested just with that, immediatelly when you accept your changes, 
your pharo UI is completelly stuck (no possible user interrupts, it is 
completelly died)