Have tried this. It's just horrible, adds nothing to the UI and doesn't work with my custom icons.
One of the many activities needed to maintain MicroStation is a Dialog Census. As the name implies we review each dialog and its tech. There are thousands of dialogs in MicroStation, so it takes some time to go through these as we use multiple UX tech. One of the BENEFITS of our STANDARD Dialog Census is the Dark Theme. So while UX dev effort was required it was part of our holistic and standard maintenance of the app.