UI compatibility across all BlackBerry devices

I wrote a simple app for the BlackBerry and tested with the 9630 simu开发者_开发百科lator. How do I get a UI design that is compatible with all the simulators?

testing, testing, and testing

If you need your app to work on all the simulators, then get all the simulators and try it. RIM does a pretty good job of making simulators available to you for a variety of devices.

Your UI has to make as little assumptions as possible on things like display size, physical keyboard etc. On touchscreen devices the screen size actually "changes" when the device is rotated. And to second @Michael, testing, testing, testing :)