@qliudr
You can be sure that I had a closer look to your source code. Very fine but it took some time to understand it 8), but I didn't manage until now to get it running on my configuration (different shield etc. ) But I will try even more.
What I took as an inspiration from your project is the use of the buttons. My shield can only show 16x2 characters and that is not enough for a tweet. So the next step will be a double array 16x10 so that I can keep the whole message and after morse output I can scroll with the keys through the message.
You can see the scrolling lines on my http://hajos-kontrapunkte.blogspot.com/2011/02/morsetweeter-v-08.html.