Our wiki contained a page (which was really more a stub of a page) on how to go about porting a Petra 2.x screen to OpenPetra.
I have updated and vastly extended that wiki page. It now also includes (Re-)Design guidance as we have vastly different capabilities with OpenPetra than we had with Petra 2.x, and the process of porting a screen should also consider whether the usability of a screen can be improved.
Here is the link to the page:
https://sourceforge.net/apps/mediawiki/openpetraorg/index.php?title=HowTo_port_a_screen_from_Old_Petra
Please have a read through it. If you have further suggestions please use the 'Discussion' feature of the wiki or come back to me.
Thanks,
ChristianK