fade_in_duration
The option documentation is properly formatted yet
Summary: Fade-in Duration on Start Default: 500 Example: 750 Since: 2.3.6
Override the fade in duration when FS-UAE starts. Specified in miliseconds. Fade in is only used when FS-UAE is fullscreen.
Source: https://github.com/FrodeSolheim/fs-uae/blob/master/docs/options/fade_in_duration