> This is probably more a question for the Seaside list than for the  
> general Squeak list, but the answer is that Seaside doesn't backtrack  
> any state it hasn't been explicitly asked to backtrack.  Along with  
> the execution stack, only objects that have been registered with the  
> session for backtracking have their state modified (and the degree to  
> which their state is modified is under their control, see  
> #snapshotCopy and #restoreFromSnapshot:).  You wouldn't register a  
> domain object like a database record (or at least, I've never found  
> any reason to) - the user expectation wouldn't be that this state  
> would rollback with the back button.  Usually you register objects  
> that represent UI state, like which tab is selected on a tab panel,  
> or whether a certain node in a tree is expanded, etc.

Thank you for this explanation. It is clear for me now.