GtkD custom theme on Windows

[Andres Clari via Digitalmars-d-learn]

I've made a linux program with GtkD, and so far, it's been pretty 
awesome, however I'm thinking about porting it to Windows also, 
but the Adwaita theme is too fugly, and cringy, so I'd want to 
use a compatible theme, which is supposed to be doable.

What would be the way to go to make a GtkD app use a custom GTK 
theme in Windows?
I tried this in the past, but never succeeded following 
documentation found online.