Pushing F3 + A re-renders the world. This is no big deal, except for the fact that A is also the key to walk left. Holding F3 doesn't cancel this out, so even if you type "F3 + A" very quickly, you're still nudged to the left.

This might not seem like a major problem, but I died once doing this while trying to get the world to fully render from a hilltop. I fell well over 23 blocks to my death.

This is probably not technically a bug, but more of an oversight, but it certainly should be addressed. Also, I've seen issues that seem like outright suggestions get fixed, like MC-1789.