VR UI Notes

UNITY GUI:
One canvas.  Its render mode is 'world space', it has a 1->100 canvas scaler and a graphic raycaster
  Its transform is just where it is in world space
  Its width and height appear to be 'pixel' width and heights, 300x500.  This may be what the 
    world scaler is about.
  But its transform also appears to have a scale factor of 0.005 (on all)

To make text pretty, up the 'Dynamic Pixels Per Unit' to e.g. 3
  
Attached to pointing controller:
  Controller Events
  SimplePointer
  VRTK_UI Pointer
  VRTK_Controller UI Pointer Events_Listener (for demo)
For text, 'overflow' is important; set to 'overflow' if you didnt give it enough space.
Buttons:
  Make an object that has a script that has a callback (AFAICT, no args necessary, but you can supply them)
  On button, drag that object into 'on click' and pick the script and callback.
  Button text is a child of the button.
For a UI where you 'turn on' the pointer via a controller click, this will work out of the box.
  For a UI where it's always on, a few changes:
    On the simplepointer, disable teleport, change visibility to "always_on"
	On the UI pointer, change activation mode to "always_on"