Comment 5 for bug 1529261

Hm, i think black is the best. Just because it adds no additional color and the contrast is good, imho. Problematic is showing the black grid on the Button. Maybe use white for the button?

The 2 images have the values from top to bottom:
gl_FragColor = vec4(.0, .0, 0., .6);
gl_FragColor = vec4(.9, .4, .1, .9);