Great job!!! This will make less horror stories and more people love GAG.
- Say as first advantage that booting the partitions can (and should) be tried before modifying the disk (MBR).
(There are just too many horror stories of people installing it with no GRUB on their PBR and accusing GAG)
- On the 'add a new OS', indicate disk e.g. disk 1 partition 5 (= first extended à la Unix)
- Populate the first configuration screen with all usable partitions, named as above (disk 1 partition 5)
(So that the user must not reconfigure each time he tries before changing the MBR)
(Or make a new action 'populate'. With appropriate icon, many users would simply use it as is)
- implement an 'update menu entry' including changing its keyboard key
(So that configuring can start from the populated screen)
- bonus: indicate version (main menu header as 'add disk' menu)