This is a really annoying issue while playing splitscreen. When my friend tries to type text on a sign, chat, console commands, command blocks, etc it prevents the other player from moving and it is really frustrating. If you can fix that, that would awesome.
I don't work for Mojang, but I am fairly sure that that is an issue with the Xbox One console. On an Xbox 360, on any game, bringing up the keyboard disables anyone doing anything in-game.