If you were to name a single button you interact with most often, it would probably be the close button, whether you're on Windows, Linux, or Mac. The close button lets you exit a program or window with a single click. So when Xerox created the world's first graphical user interface-based operating system, "close" has to be the button they came up with first, right?
Wrong. As students of early computing history know, it was the hamburger button, that triple-tiered catch-all button that designers love to hate. But the close button came next, right? Nope. In fact, it wasn't until Windows 95 that the close button existed at all.
Over at the PlaceIt Blog, Karla Urbina traces the history of how title bar elements became standardized. No matter what operating system you're on these days, the buttons in your title bar tend to be fairly standardized: they might differ in appearance, or even placement, but across Windows, Mac, and Linux, every title bar has a close button, a minimize button, and a maximize button.
But as Urbina points out, it took a long time to get here. Despite the fact that Xerox created the first graphical user interface in 1981, the title bar didn't even come close to being standardized until 2001, when OS X and Windows both came to a rough consensus on what the buttons in a window should be, and what they should do. Linux followed suit, and the rest is history. But before that, if you were a Windows user, doing something as simple as minimizing a window on a Mac was like solving a UI cipher.
This is a design lesson in its own right: no matter how standardized a UI/UX solution (like the placement of title buttons in an operating system) might seem, it's just one great idea away from evolving into a new, radically different standard.
[h/t Sidebar]