I'd like to thank everyone who made this possible;, including but not
limited to Riakodoadm, MrThatKid, kyzentun, Luizsan, JoseVarelaP,
everyone else who provided feedback and bug reports.
As noted in my previous commit message, I think ThemePrefs.ForceSave() can safely be deprecated. Since many novice themers look to default when learning, I think it's better to use ThemePrefs.Save() as the system was originally designed.
I moved the ThemePrefs.Save() call out of ScreenTitleMenu decoration to ScreenOptionsService in. This seems safer to me; Pay/Freeplay never hit ScreenTitleMenu which could be another reason ThemePrefs would never get saved.
Additionally, moving the call to ScreenOptionsService in also seems to have fixed a bug where switching themes via the Appearance Options service menu would cause the new theme to inherit all of the previous theme's ini settings. I'm still not entirely sure why.
I've done a fair amount of testing with this.
I've tried deleting the ThemePrefs.ini file outright and booting fresh into both default and Simply Love. In both cases, the ThemePrefs.ini file is written when StepMania exits or when the user hit ScreenOptionsService, whichever comes first.
I've tried switching between various themes, including those that did not use ThemePrefs. I haven't seen any sections being created erroneously and themes that do use ThemePrefs don't seem to inherit the previous theme's settings any longer.
Still, it *very* possible that I've missed some edge case(s) and is probably worth a few people testing before merging.
ListenerJubatus