>15 is better than 10, of course :) But when would we have a button right at the bottom of the message to see the whole thread?

I am not sure about that because there is a limit. I have found that in the past that option was really CPU intensive. So, before we were allowing it but with the map on top and up to 50 messages at a time. This had to be revised. For now, thread map and the selection of the desire messages seems to be a safe way.