The Wall Street Journal has a rare inside look at Apple’s internal workings through its interview with original iPhone software engineer Greg Christie. According to the newspaper, it’s the first time that Christie has opened up about the project.

While Apple is normally highly secretive about its product teams, it approved the interview in hopes of bolstering an upcoming case against Samsung by sharing how it came up with the iPhone’s many innovations:

Mr. Christie’s team pored over details like the perfect speed for scrolling lists on the phone and the natural feel of bouncing back when arriving at the end of a list. He said his team “banged their head against the wall” over how to change text messages from a chronological list of individual messages to a series of separate ongoing conversations similar to instant messaging on a computer.

You might recall a similar story last year from The New York Times, but this a new chance to hear from Christie, who worked on the Newton and is listed as the inventor of the “Slide to Unlock” patent for the iPhone.

Apple Engineer Recalls the iPhone’s Birth [The Wall Street Journal]

Image credits: Tony Avelar / AFP / Getty Images