I can also confirm the hotfix sp0 patch 1 fixed the issue (almost). There is still a small issue when using the back button.
Press a button (e.g. named "app 2") to do the APPLICATION.openNewWindow(), and it opens another Design Studio application just fine.
Press the back button, press the same button ("app 2"), it is now just showing a blank page..
Regarding Nikhil's original question - about new features in 1.3 SP1, does anyone know where a list of items for SP1 can be found?
According to SAP, it should be released next week:
https://websmp208.sap-ag.de/bosap-maintenance-schedule
I found a schedule mentioning note 1992588, for 1.3 SP1 but can't see anything on it.