01-07-2011 03:35 AM
As far as I know, no there isn't. You do have to calculate in the factor the the Playbook is a 7" mobile touchscreen device and people are not able to hit a 5x5 button. You could always take a screenshot of your app, resize the image to the actual screen size of the Playbook and print it for a usibility test.
01-07-2011 08:11 AM
I've been using 45px as the min height or width of something. I've gone down to 35 in a couple of places to match the height of the text input field, but I will probably need to change if the hit area conflicts with neighboring items. Without a real device, it is hard to test at this point.