To switch to windowed mode when playing the game through the PC launcher, follow the steps below:

[ROM Fullscreen Mode Activation/Deactivation Method]

On the game screen, click on the menu located at the top right corner → Settings (gear icon) → Environment → Click on 'Graphics' on the right side of the screen.
In the Environment - Graphics - Environment Settings, click on the [Turn Off] button next to Fullscreen.