How to expand a Control object to fill its H/Vbox container in Godot 4

Been struggling with this for too long before discovering this, made this video so you don’t have to. Tested with Godot 4.8, but this feature has probably been around since 4.0. My links: https://linktr.ee/mousepotatodoesstuff [https://linktr.ee/mousepotatodoesstuff]