The patch by Phirel allows one to run Minecraft in full-screen mode but only in survival, and I wanted creative. So I modified the patch to work with creative mode. Moreover, I wrote a combination of a shell and python script that adds the ability to exit by pressing alt-f4, alt-4 or alt-x. (Not all Bluetooth keyboards will support all these combinations.) All the stuff is here.
On the latest Raspbian, you can install all of this via:
Upvoted. It always did bother me that Phirel's mcpifull.bsdiff was actually fullscreen+survival.
FYI, last year somebody figured out the surprisingly simple way to switch between full screen and windowed dynamically. It turns out you just need to press Alt+F11 at the right time. See WillBoxOwO's post on the Pi forums.