I was looking how to properly use WATransaction decoration (#isolate:) to prevent the backbutton usage, and found this message from Ramon Leon in the Seaside mailing list:
#isolate: is used to wrap what is essentially #call: to several
components in succession. You could use isolate in a callback, if the
callback is calling another component to display, but not if it's just
setting instance variables.
The point is, all isolate does is expire any components created within
the block passed to it, when the execution of the block is complete.
Once execution has passed beyond the isolate block, the user cannot go
back to any component called from within the block.
Now I get it.