Lock mouse cursor to GZDoom window.

[Accensus]

Occasionally I'd stream on Discord and put the chat on the other monitor, but sometimes, while looking around in-game, the invisible cursor would leave the (fullscreen) GZDoom window and get positioned over the chat, which causes the scroll wheel to move the chat up and down. Is there a way to lock the cursor when the focus is on GZDoom?

[Accensus]

Looking at the comment above this line makes me think this might actually be a bug because the cursor is most definitely not locked to the window. Unless I'm missing something here.