constructor(parent) {
    super(parent)

    this.flexDirection = 'row'
    this.fontSize = 0.02
    this.itemHeight = 0.04
    this.padding = [0, 0.02]
    this.backgroundColor = 0x444444
    this.borderRadius = 0.01
    this.alignItems = 'flex-start'

    this.data = {}
  }
THIS IS A WORK-IN-PROGRESS.

`DatGuiFacade` creates a UI panel for tweaking a set of values, along the lines of
the well-known [dat.GUI](https://workshop.chromeexperiments.com/examples/gui) or
[react-dat-gui]([react-dat-gui](https://github.com/claus/react-dat-gui), for use within
WebGL environments. This is particularly useful in WebXR, where overlaid HTML cannot be
used. It is interactable via both screen mouse/touch input and WebXR pointer inputs.

@member {DatGuiItemDefinition[]} items - Defines the list of values to be presented.
@member {object} data - An object containing the current values for each of the `items`.
@member {function(object)} onUpdate - A function that gets called when the user changes any
        values. It is passed the modified `data` object.
@member {number} [itemHeight] - Default height for the items.

This extends {@link UIBlock3DFacade} so any of its supported properties can also be set.