Knowing when to break the rules

One thing which has irked me a lot recently is a piece of UI "correctness" that I've noticed when using Chrome.

Note the screen shot below:



If you can manoeuvre your mouse into the area that I've circled (in between the tab and the "plus" button) and click and drag the mouse around, you'll notice that the entire Chrome window starts moving around. The reason for this is that when you click this area, you are (essentially) clicking on Chrome's title bar and (as a feature with most OSes) when you click and drag a window's title bar, you are able to alter the position of the window.

What's wrong with this behaviour? Nothing really. It is extremely hard to trigger, and when triggered (and after having a good look at the UI) relatively easy to figure out why your Chrome window has repositioned itself about 5 pixels to the right, instead of opening a new tab.

Sometimes though it's ok to break the rules.

There's a rule in computer science called Fitz Law, which talks about how easy it is for a person to click on something on the screen with the mouse.

Long story short, the easiest places for a person to click are (in order of easiest to hardest)

1. Where the mouse is currently
2. At the edges of the four corners of the screen (all four corners are second equal)
3. And all third equal, anything hard up on any sides of the screen, i.e. hard top, hard left, hard right, and hard bottom of the screen
4. And for the purposes of this example: everything else
   

The reason is that to hit these positions, you can just "flick" the mouse right to each of the four corners of the screen (or to the hard left, hard right, etc) and don't have to slow down to find the exact spot, or go back again if you've overshot.

If you're using a Mac, to open the Apple menu you don't have to click right on the "Apple" icon (even though the screen shot below gives that impression). Just click on the top left hand corner, and the menu opens. Same with the spotlight window (on the top right hand corner).



If you're on a Windows machine, same with the Start menu and also the Task Bar. Notice how though, on the Task Bar (below) each task box doesn't actually extend to the bottom of the screen. If you click hard bottom of the screen, underneath the task, the mouse will actually "jump" up 3 pixels and selects the task (go on, give it a try if you don't believe me).


Which brings me back to Chrome's title bar "bug" which should (IMHO) open a new tab if the surrounding area around the "plus" button is clicked.