2020 Fusion and 2020 Fusion Live (version 8.6 onwards)
1. Go to File Options General.
2. In the User Interface Options section, click Colour Scheme: ▼ drop down selector and change the selection to Black and click OK.
By default the Design Window will adopt the User Interface Mode.
3. This can be changed as a global setting in File Options Render Settings.
In here, you can select if your design window is White, Black or Adaptive depending on the selected user interface.
You can independently switch the design window mode by right clicking in the design window and choosing Switch Background.
Some example screens below:
File Screen (Connect Mode):
File Screen (Standalone):
Plan View (with Coloured Lines option enabled):
Elevation View:
Perspective:
The design window dark mode is effective in Wireframe and White Fill renders. Colour Fill, Draft, Presentation, Presentation+ and Publish have not changed.