In our flow definition we use a recursive call of the same flow definition. So it can happen, that during flow execution the same view-state is reached several times but in different subflow calls. We implemented our system with version 2.0 M4 and now updated to release 2.0.4. With version 2.0 M4 the ids of the execution parameter (execution=e1s2) increased with every click on any button of any view. Even if the click ended in a recursive subflow call, which ended in the same view-id again. For us, this behaviour is the required behaviour in order to enable the use of the browser back-button.
With release 2.0.4 we now encountered a problem. Whenever a new subflow is started the execution parameter does not change. Thus, the browsers back button does no longer work correctly.
Thanks for your help!