Allow other programs to grab cursor

I'm not able to lock my system with i3lock/slock when hhpc is hiding the cursor. i3lock complains with 
```sh
$ i3lock
i3lock: Cannot grab pointer/keyboard
```
As a temporary work-around I terminate hhpc in a wrapper script and restart it when the i3lock process (non-forking) ends.

I'm know not a smidge when it comes to X interaction, so unfortunately I can't help much.