I noticed sometimes, when I exit the crafting GUI for the Werkbench, usually after clicking anywhere in the dark area around the GUI, my mouse cursor stays visible, while still affecting POV.

This video might make more sense - https://youtu.be/N5Wb9TiPNzE

Yup, I just realized I left a Mouse.setGrabbed(false) debugging call in the container code. It'll be fixed in the next alpha, thanks for reporting this!

Fixed, closing.