How to I create a top level ui element that will disable player input when visible?

[votan]

Originally Posted by chatrat12 After looking at the scene/fragment model, I see that fragments wrap around your control. So, I don't necessarily need a custom fragment.

All the fragment "classes" you need are already there. For you own top level you need your own ZO_FadeSceneFragment "instance".
To stop all movement you can re-use STOP_MOVEMENT_FRAGMENT instance.