I attended a small dinner party in 2005 when I was a student at Santa Clara University. Our special guest was Douglas Engelbart, inventor of the computer mouse. Englebart died Wednesday.

I asked Engelbart what he thought of Apple's first two-button mouse. Apple had just introduced its Mighty Mouse, which had four functional "buttons": left and right capacitive sensors, a track ball with a pressure sensor and side squeeze sensors. Apple had steadfastly sold a one-button mouse for years.

Engelbart answered that he would like to see a mouse with even more buttons.

Defending a multi-button mouse, Englebart explained to the group that immediate learnability should not always be the goal of a hardware device or a software interface. In many circumstances an effective interface may be complicated and challenging to learn. Englebart offered the keyboard as an example of a complicated input device. It takes considerable time and effort to learn touch-typing, he said, but once mastered, you’ll enjoy a lifetime of fast text input.

This was a bit of an epiphany for me. I had been such an advocate of Apple hardware and its easy-to-use interfaces, that I had blinded myself to the benefits of more advanced interfaces that may require some time to learn. I realized that some of the best interfaces I used on a daily basis were somewhat unintuitive. I’ve memorized hundreds of key commands, I’m a master of Photoshop’s intimidating menus and palettes, and today I make extensive use of Quicksilver’s many features. I’ve even found myself craving the power that comes with even more complicated interfaces such as that of VIM.

What I’ve learned after reflecting on my experiences is that it’s important to consider your audience above all else when designing interfaces. The user's experience is the only thing that matters when it comes to interface design. Just remember who that user is, and realize that ultimately, the best interface experience may be one that requires learning.

Your interface should also provide an easy introduction, and plenty of power when needed. The Macintosh embraces both of attributes beautifully. I try to incorporate this thinking into my product, Flinto, as well. Flinto’s interface is very visual, and is meant to be very straightforward, but shortcut keys exist for almost every common command. I hope to expand this even further in the future, giving more power to those who crave it.

Take a moment to appreciate the contributions Engelbart made to human-computer interaction. Read his biography, and read his obituary in the New York Times. And next time you design an interface, add a few extra buttons for Mr. Engelbart.