Coming Undone

TO come undone is to be ruined. With computers, you can often avoid this state by using the undo command—a feature we take for granted until we need it to bail us out of a spot of trouble.

Webopedia defines undo as a return to a previous state by undoing the effects of one or more commands. For example, if you're working on MS Word or OpenOffice Writer and accidentally delete a block of text, you can quickly recover it by going to the Edit menu and choosing "undo" or typing its keyboard shortcut, Ctrl+Z, or Command+Z on a Mac. Conveniently, this feature works on multiple levels, so you can go back and undo a number of commands starting from the latest to the earliest.

Multiple undo is particularly handy for graphics programs such as Adobe Photoshop, where using the wrong filter can quickly turn a promising photograph into a gray mess. On Corel Draw, having multiple undo levels encourages users to experiment with different visual effects, secure in the knowledge that if they screw up, they can always retrace their steps to an earlier stage of the illustration.

It wasn't always that easy to recover from mistakes.

In the late 1970s and early 1980s, the most popular word processing program, WordStar, had no undo command. Before Version 6, MS Word had only one level of undo. And strange as it may seem, Photoshop didn't have multiple undo until 1998.

Today, multiple undo is built into most applications but operating systems feature only the most rudimentary forms of the command. If you delete a file by mistake in Windows or Mac OS X, you'll be able to recover it by pressing Ctrl+Z or Command+Z, but only if the file is still in the trash or recycle bin. Ubuntu Linux has no similar command. To recover a file, you must click on the wastebasket and drag the file out.

Operating systems take a different approach to keep users from doing serious damage. For example, if you try to format a hard drive, Windows XP and Mac OS X will pop up a dialog box that asks if you're sure you want to erase all the data on the disk. In addition, Linux and Mac OS X will ask for an administrative password to make sure the user is authorized to make such drastic changes. Somewhere along the line, so the theory goes, the user will actually think about what he's going to do before he does it.

But the late Jef Raskin, who designed the original Macintosh interface, held that confirmation dialog boxes were a bad idea because people eventually click on "yes" or "OK" by habit, without understanding what's going on—until it's too late. It makes more sense, Raskin said, to have a general undo command that worked consistently throughout the system.

Anyone who has mistakenly overwritten a file and realized it the split second after clicking "OK" will appreciate Raskin's point of view.
Raskin left Apple in 1982 after Steve Jobs took control of the Macintosh project and went on to design a computer called the Canon Cat, which featured a prominent "undo" key where the backspace key is on most modern keyboards.

Unfortunately, the Cat didn't catch on—and neither did the undo key.

Nobody seems to know when undo became a standard feature in software. Alan Dix of Lancaster University, has studied human-computer interfaces extensively and notes that as early as 1984, undo was already considered an important part of most sophisticated systems.

Beyond the obvious task of returning a document or file to its previous state, undo is really designed to reduce risk by helping users recover from errors, Dix writes.

The problem is that undo doesn't always work the way users expect it to. Certain commands cannot be undone, and sometimes, you can lose track of where you are in the undo history. I imagine these problems become even more challenging at the operating system level.

Still, some undo is better than no undo. I've often wished for an undo switch that worked in the real world—but that's another story.