automatic_input_grab
The option documentation is properly formatted yet
Description: "Grab Input on Click" Default: 1 Example: 0 Since: 1.3.23 Type: boolean
By default, FS-UAE grabs the mouse and keyboard input when you click on the window with the mouse. You can prevent this by setting automatic_input_grab to 0.
Source: https://github.com/FrodeSolheim/fs-uae/blob/master/docs/options/automatic_input_grab