[Seaside] show active page after hitting isolated code

[radoslav hodnicak]

say I have

self isolate: [self showA].
self isolate: [self showB].

when I'm on page B, hit the back button to get to page A and click an 
expired link - how do I get to show page B again (automatically) instead 
of the not very helpful "Page expired, use back button blah" message?

In Seaside 3.0. Do I have to write my own filter, or is this burried 
somewhere in the configuration catacombs?

rado