Please consider that going to the "dark side" has more problems than programming for some of us. IF the contrast is not good, a lot of things can't been seen by some. V3 went dark, and it caused problems until the pallet was adjusted to make any text and imagery (icons, lines, etc.) stand out. (There are still some things needing adjusting.) xLights has been wonderful because it stayed in the light.
Well, the problem is that, at some point, xLights won't have a choice. ANY application compiled with Xcode 10 will AUTOMATICALLY be in dark mode for any system controls (text fields, lists, tab views, drop downs, etc...). As far as I can tell, there is no way to opt out of it. The only way is to compile with Xcode 9.4. However, with 9.4, you can then not opt-in to dark mode. Once Xcode 10 is "released", it will be very difficult to get 9.4 (based on history with Apple) . Thus, at this point, I'm trying to make sure it's usable in dark mode. If the system is set to Dark mode, it will display in dark mode. If set for light, it will display in light. The application doesn't really have a choice for the parts that are built with system controls. For the stuff not built with system controls, all we can really do is query the system colors and try to find something that will work with them.