Put the summary of the bug you're having here
What I expected to happen was...:
I would have closed my inventory as usual.
What actually happened was...
Nothing was responding, and I couldnt leave, but the world still moved around me.
Steps to Reproduce:
1. move your boat at full speed, and glide, while gliding open inventory and wait until it stops.
2. ...
3. ...
Have you tried clicking out of your minecraft window?