Output was displayed on 5" CRTs. High-resolution TV cameras (875-line) transmitted the CRT output to 17" monitors at each work station. By flipping a switch, the video could be inverted, so you could get either black lines on a light background or white lines on a black background. In other words, Engelbart invented dark mode :-)
Plausibly someone else in Engelbart's lab, or a group of people, invented it. He always complained about people assigning him credit for the whole team's output.
I vaguely remember the published description of TREE-META crediting META-II, though I might be confabulating that. More broadly, I don't think any compiler-compiler is unrelated to META-II.
