I've been playing around with this with some success. It seems though, that it only applies the last loaded Widget.sublime-settings file to take effect. Is that the expected behaviour?
I have the assets set up like this:
/Theme - Soda
Widget - Soda Dark.tmTheme
Widget - Soda Light.tmTheme
From here, I was hoping to have the Widget.sublime-settings file loaded that related to the selected theme.
So if "Soda Dark" was loaded, it would ideally use the Widget file from "Soda Dark/Widget.sublime-settings", which contains a single rule pointing to the tmTheme file that allows control over the text fields.
I'm guessing the way things are set up that it pulls in both Widget files inside "Theme - Soda" and then whatever the last one pulled in, being the one that's applied?
If that's the case, it looks like I'd need to break the theme variants into their own separate "Packages" level theme folders if I want per variant widget control.