Chat box registering keys before pressing ESC

So I was testing the newest snapshot (I believe that's 15w51b) and I inserted a command (/gamemode survival) as I was going to fight the new enderdragon, so when I pressed ENTER, I jumped. (I'm used to playing on the right side of the keyboard, so I use ARROW keys to move, ENTER to jump, etc.) I thought this was an addition for commands, but when I said something(which means typing something after pressing 'T') and I pressed enter, I jumped. Please fix this as it will be really irritating during Pvp or Hide-and-Seek.

Here's a video:
https://youtu.be/U6493jSAPEs