easy way to do:
create a popup. you put the popup at the bottom of the scene and turn on the popup when you don't want that user to do anything else. make sure the mouse filter is set to stop. you could put a label on the popups so the user doesn't think the game crashed or locked up.
the other way to do is have a container that the mouse filter is set to stop but as a new scene. that way you would have to generate a proper system system or popup system. the first way is easier to do though.