initial_input_grab
The option documentation is properly formatted yet
Description: "Grab Input on FS-UAE Startup" Default: Example: 0 Type: boolean
By default, FS-UAE grabs the mouse and keyboard input when it starts. You can prevent this by setting initial_input_grab to 0.
Source: https://github.com/FrodeSolheim/fs-uae/blob/master/docs/options/initial_input_grab