Brilliant! Absolutely amazing. I wished to have had tutorials like these at the time I've started with AHK (while it was still a fork of AutoIt!)
You adopted Chris Mallet's attitude to keep it simple - one of the toughest challenges. Well done!
Hope to see some more
PS: I seem to remember that you can change the filetype options of a save-dialog with swapping its values at the registry (RegWrite).
PPS: Degustibus non est disputandum ... but the color setting of your windows ... *can't find a smiley to express my feelings*