We used the ddp packet layer that was available in Linux's kernel along with Netatalk version 1.3.3 for the AppleTalk networking. Motif was used for the X interface. The packet format Broadcast was expecting was derived from a very old document we found about Broadcast.
The chooser screen has the main disadvantage of being in the Chooser. It is a royal pain in the tookus to open up the chooser each time you want to send someone a message. However, from this box, you select the AppleTalk Zone where the person you want to send the message to lives and then his or her name from the box at the right. Also in this box this gives you the opportunity to select wether you will receive messages or not and if any incoming messages will appear in the forground or quietly appear in the background. Most people keep it set in background mode.
After selecting who the message will go to the "send-message" dialog box will appear. In this you get to select the icon you want to send, as well as enter your text.
The message box is what is displayed with an incoming message. As you can see this one was in the background when the screen shot was taken. The icon is shown along with the message. We have send the Linux Broadcast icon for this demo shot to show that the icons are actually being sent across the network.
We've combined the functionality of the chooser screen and the send-message box into one.
Our message box is about the same as the Macs, just a little cosmetic difference.