S40 Nokias do weird things when you put a StringItem on a form, give it a label but no text. It will prevent users from scrolling that form.
S60 Nokias do some weird stuff too, but only sometimes. Best not to do this.
SonyEricssons, on the other hand, retain image size on ImageItem when you setImage(null). You have to set a dummy 1x1 image first (or instead).
And last but not least, with certain bluetooth devices (GPSr's, in this case), Nokia phone would perform a bluetooth service search, but return error instead of the service.
When you're searching for a serial port service (UUID 0x1101) and get an error instead, just take "btspp://" + RemoteDevice.getBluetoothAddress() + ":1" as a connection url and you have a solid chance of connecting successfully.
(That means BT address + channel 1. On single-purpose devices, you'll most likely find the only service on channel 1. Makes sense, eh?)