message: mol-plugin: warn if viewport canvas changes ref
diff: @@ -124,7 +124,10 @@ export class Viewport extends PluginComponent<{ }, ViewportState> {
  return <div className='msp-viewport'>
  <div className='msp-viewport-host3d' ref={elm => this.container = elm}>
  - <canvas ref={elm => this.canvas = elm}></canvas>
  + <canvas ref={elm => {
  + if (!!this.canvas && this.canvas !== elm) console.warn('changed viewport canvas')
  + this.canvas = elm
  + }} />
  </div>
  </div>;
  }
  