Mizipzor's Weblog

Opera 10.51 blatantly fails at Fitts’ law

March 24, 2010 at 20:46 (Web) (browser, design, fitts law, gui, opera)

I just updated my browser, to Opera version 10.51 (recently switched from Chrome), and something strikes me as odd. Its hard to switch the active tab. It turns out that the designers aren’t, apparently, aware of Fitts’s law. In a strange twist of fate, this most important law in GUI design was just today given some attention in the (close to legendary) blog Coding Horror. Jeff Atwood also links to a great visual summary of the law so there is no need for further explanation here.

So where does Opera go wrong? Well, in its most extreme summary Fitts’ law states that the larger a button is, the easier it is to click. Simple and logical. Heres a screenshot of Opera and one of my open tabs:

The topmost two pixels aren’t considered part of the tab, so by moving my mouse cursor to the very top of the screen I can’t click the tab. I must stay put on it. This is bad.

Why is it bad? Because the mouse cursor can’t be moved outside the screen. Once it reaches the edge it stops. Thus, by placing a button at the edge of the screen, its width/height (and therefor size) is infinite. And, according to Fitts’ law, infinitely easy to click!

This is far from something new. According to Wikipedia, Paul Fitts proposed the law back in 1954. And Jeff Atwood has written about it before, close to three and a half years ago he touched on this exact same problem; the infinite size of buttons placed at a screen edge.

OSX places its menubar buttons at the top, by the edge of the screen, rather at the top of each window, which is more common. Thus giving them infinite height. Its about the only thing it does right when it comes to GUI design but it works. And really good at that.

Google Chrome understands Fitts’ law. Why doesn’t Opera? Why?

And how do you, by the way, correctly spell Fitts’s law?