Hi!
I added water material (latest from Github repo) to my BJS (2.3 alpha) scene, showed it to my friend and got back print screen below. It also flickers from time to time.
Graphics card is Nvidia Geforce 550 Ti, with latest drivers (updated today)
Issue can be reproduced on BJS Playground in the materials section for water: http://www.babylonjs-playground.com/#1SLLOJ#17
