I'm fairly certain that exact thing existed on Windows XP and earlier. It was a question mark in the top right of the window, added a "?" next to your cursor. You could then click elements to see if there happened to be an explanation embedded in the program for that particular button/box/whatever. Didn't always work, but was useful when it was needed.

> Here's a solution off the top of my head: have a dedicate "info" button at the OS level. Holding the button disables normal interaction, highlights all inspectable elements, and allows you to click on each one for a description. Like "inspect element" in the browser.

This is a really cool idea. Agreed! Wish something like this actually existed.

Wait, isn't that what Windows 3.1/95 did with the "What's this" button?