That's how maps work by default. It's a cheat to pull the map up that way. But it just shows you the map in the Use Item screen like King's Field does it. Before the project is finished It will be possible to bind any item (incl. maps) to a button like pressing Start to use an item in KF. But I don't know if it's good to officially support a real-time map. That feels like one of those things modern games may provide that shouldn't be on the table. But you can use the Alt+Alt+M system to turn it on and it will be remembered after you turn the game off so you never have to do it again. Or bind it to buttons like in this demo.