Is MainScreen compulsory in BlackBerry applications?

Currently I've got 2 screens utilizing almost the same functionality and I'd rather extract common logic into some base class but the extend different RIM UI clases: MainScreen and FullScreen. Due to there's no multiple inheritance in java I cant figure out how to do this unless they both extend FullScreen. So the question stated in title arises. I've tested with 4.2 simulator and it works ok without the MainScreen, but I'm not sure for all the OS's out there. 开发者_如何学运维Does anyone know?

Cross-posts:

http://supportforums.blackberry.com/t5/Java-Development/Is-MainScreen-compulsory-in-BlackBerry-applications/td-p/383883

http://www.blackberryforums.com/developer-forum/211205-mainscreen-compulsory-blackberry-applications.html#post1511361

Simply put, no it is not mandatory to have MainScreen in Blackberry applications.

MAIN screen is not compulsory, we should use main screen only when we have to provide UI to the users. SO, its not mandatory.