The white on white trick, nasty.

Reminds me of a story of a practical joke I heard from someone.

Someone in their office had a computer CRT screen which had separate cables for red, green and blue and they swapped these cables around.

But this was also back in the days of Windows 95 where pretty much all applications respected Windows’ colour scheme. And they also changed all the colours so that all the UI element colours still appeared correct with the mixing of the monitor’s input cables.

This had the effect that in applications only icons looked wrong, or pictures in their documents.

Apparently took IT a little while to work out the issue.