Er, before I start - great game Hubert
When saving a turn with the same name as a previous saved game the 'Overwrite existing file' message is displayed.
Clicking 'Yes' redisplays the save game box.
Clicking 'Yes' to save shows the 'Overwrite existing file' message again.
Clicking 'Yes' a second shows the Save game box, this time 'Yes' time saves the turn.
Couple of suggestions for the Load saved game screen.
The sort order is alphabetical which could be confusing when multiple saved games are in progress and you haven't used some sort of naming convention.
Also the date and time saved being displayed would help and maybe a choice of sort order for the list.
Finally, doubling clicking on an entry rather than selecting then hitting the Load button would be easier when using the touchpad on a laptop.
Er, and BTW, great demo Hubert