Yay, I was able to make my Preferences go dark with 5 lines of code. Great stuff!
I had to comment out line 104 of DarkMode.h though...
void SubclassDialog(HWND);
If present, it won't compile.
3>Z:\Git\foo_jscript_panel3\foobar2000-sdk\libPPUI\DarkMode.h(104,7): warning C4003: not enough arguments for function-like macro invocation 'SubclassDialog'
3>Z:\Git\foo_jscript_panel3\foobar2000-sdk\libPPUI\DarkMode.h(104,7): warning C4003: void SubclassDialog(HWND);
3>Z:\Git\foo_jscript_panel3\foobar2000-sdk\libPPUI\DarkMode.h(104,7): warning C4003: ^
3>Z:\Git\foo_jscript_panel3\foobar2000-sdk\libPPUI\DarkMode.h(104,7): error C2059: syntax error: 'constant'
3>Z:\Git\foo_jscript_panel3\foobar2000-sdk\libPPUI\DarkMode.h(104,7): error C2059: void SubclassDialog(HWND);
3>Z:\Git\foo_jscript_panel3\foobar2000-sdk\libPPUI\DarkMode.h(104,7): error C2059:
VS2022 17.4 Preview 1, v143, stdcpplatest if it makes any difference