2D GUI example that shows how a modal dialog could work and also in a scenario that will work in XR/VR.

NOTE: a full screen GUI does not work in VR, but a GUI on a Plane does - you can supply the prop createForParentMesh on the ADT:

<plane ...>
  <advancedDynamicTexture
    createForParentMesh
    ...
  >
   ...
  </advancedDynamicTexture>
</plane>

Click on one of the boxes to trigger the GUI modal: