Loren Brichter, the guy behind the fantastic Twitter application Tweetie, has a post over on his blog talking about how and why he chose to put specific items on the bottom bar of Tweetie’s UI. The post is a quick read, so go take a look; I’ll wait.

Welcome back. One of the things I found interesting about what he said was that he chose the items for the bottom bar based not on what was most common, or most popular, or most used, but rather another characteristic that they all share: they’re all personalized features about the user.

This isn’t really earth-shattering, but I found it interesting because in most cases, UI designers try to make sure the most commonly used things in the UI are surfaced. The problem with that approach, as Loren points out, is that you can’t always do that. Sure, Copy and Paste are super-common, and should get first-class treatment, but where do you go from there? At some point, you’re splitting hairs, and if you try to rationalize why one function is surfaced in a prime location and something else isn’t, how do you explain your choice? “Well the data we collected said 51% of people used A and 49% of people used B, so we went with A.” Unsatisfying, isn’t it? At least if you take Loren’s approach, your answer has a bit more meat to it.

Anyway, at the very least this should get us all thinking about our rationalizations for putting stuff in specific places in our UI. Maybe there are alternative methods for making these decisions that we haven’t considered yet…