In a way you can already block movement if you want to, just open the main menu, it blocks movement. 
You might want to look into setting the deadzone in SteamVR if you have drifting Index controllers though.
In a way you can already block movement if you want to, just open the main menu, it blocks movement.
You might want to look into setting the deadzone in SteamVR if you have drifting Index controllers though.