Eisenhans: Sorry it was late, I meant "this type of comment" (as in this "personal attack" without more informations in regards to the topic itself) not "your type of comments" (as in "your general comments").
@Kazan: Also Eisenhans screenshot does bring an interesting point like yours, it is not a matter of monitor (since people who executed the capx and had similar color on their monitor do see the different colors in your screenshot as well, meaning when you are executing the WebGL shader, the result is different RGB colors, whereas it is not on other peoples' computer).
It could be a matter of graphic card/chipset.
Strange indeed that running the provided capx as is results appear so different from a computer to another.
For people trying, please can you put your computer specs (OS/Graphic card/NW.JS version I guess should be enough) to see if some trend jumps out ?
Mine : Win 7 pro, Nvidia GTX 560 Ti, NW.JS 18.7 then updated to latest NW.JS 19.4 and still the same result of the same color for both objects.