Rated 5 out of 5 stars

le Vojtano ar Lún. 2, 2016 ·

Don't trust that other comment. It works this way, but you must have an AMOLED screen. I do have it and this is exactly what makes my firefox more efficient.
It's a must for all AMOLED screen users ;-)

Rated 1 out of 5 stars

le JamesMP80 ar DFómh. 30, 2012 ·

the color of the screen does not affect the amount of power used the back lighting is what consumes power and even on a screen showing all black the backlight is still on