Maybe this has happened to you. You went to copy a quote from a press release and, suddenly, this is what you saw:
I couldn’t figure out what the hell had happened, but my screen was suddenly gray. It was at the correct resolution, and everything looked the same except it was gray. At first I thought I’d mistakenly turned on high contrast mode (which you do with left Alt+left Shift+PrtSc) but nope.
A little digging led me to the dialog shown in the image above. Apparently Windows has a “color filter” mode that, when invoked, makes it easier to see certain colors. It’s intended for people with color-vision deficiencies. For ease of use, Microsoft tied it to a key combination: the Windows key + Ctrl + C. I must have accidentally bumped the Windows key while copying my quote.
Now you know.