The ability to print out a character sheet (whether to an actual printer or just to a PDF file for portability) would be very useful.
Arguably this is a secondary idea, but potentially the ability to map fields from a FG character sheet over to...
I'd like to see more character creation and advancement functionality in FG. I've actually grown quite accustomed to using FG at the tabletop even just as a player when we are not using FG for any other function (some of my GMs don't have laptops...
I would like to offer a suggestion for adding, among the the other available attack selections (Arcane, Melee, Thrown, etc.) one for Opposed Rolls. That might get tricky, I suppose, but at the least I might suggest the most common ones of...
