Don't have the scene update, you can use a script call to catch processing in another loop, but remember that Graphics.update has to be called, or the game will crash after a few seconds. Do something like this in a script call:
loop {
Graphics.update
Input.update
break if Input.trigger(Input::B)
}
I just threw in the ending if the B button was pressed, but remember that you MUST have some condition of breaking the loop.
You can have it set to a number of seconds as well like this:
120.times { Graphics.update } # 3 seconds
Or, to simply freeze the graphics, you can use Graphics.freeze, and then Graphics.transition to restart them, though this will simply make it so that things don't appear to change. If they "move" while the graphics are froze, they will suddenly reappear in their new location when they are transitioned back, which looks funny.
You can get away with it if you are cleverly with fading the screen out first, etc, but all that is determined by what you are using it for.