when entering a world and opening a new window and waiting a while you cannot enter the

Put the summary of the bug you're having here

What I expected to happen was...:
when entering a world and opening a new window and waiting a while you cannot enter the minecraft
you need to read it
What actually happened was...:
i dont remember

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...