Just found out something

- you are reading a message
- you click at the bottom 'view the map of this thread'
- you then check the first message
- you click 'view' .. this shows the first message.
But at the bottom, the 'view complete map' icon has a green arrow and its tooltip : 'view the map of this thread in the above frame'

If you click that, you get the whole thread in the upper frame - as if all the messages were posted today.
In the upper frame you can then click on any message and its contents will be displayed in the lower frame

Dunno since when this is possible