A-Button (short & long push) to create letters in international morse code. If not pressed for some time a new letter is assumed, displayed and added to text.
B-Button (short) deletes the last letter from text
B-Button (long) displays text for review
A&B-Button sends text to other micro:bit as textmessage and shows new recieved messages since last check.
If a message was recieved the top left LED will light up to indicate a new message.