Flexible vs Inflexible User Interface

Today while reviewing a project to add customizable hot keys to our product that a couple of our summer interns were working on a suggestion was made that got me to thinking about flexible vs. inflexible user interfaces and what is better.

The suggestion was that we not allow the arrow keys to be reassigned to other commands. On the surface this seems like a bad idea. Why would we prevent the customer from making the commands that are currently associated with the arrow keys be reassigned to something else?

To answer that question is to understand a bit more about what makes a good user interface.

A flexible user interface is nice because it allows you to do pretty much anything you want. On the other hand it may make doing very common simple tasks harder to do. An example of this is what makes computers work. Machine language is a very flexible user interface. You can use it to create any software that you want. On the other hand it can be nearly impossible to deal with for a reasonably complicated system.

A higher level language is less flexible but you can be much more productive. In C++, for example, a single line can generate more instructions than a room full of monkeys.

This gets to main point, simple interface may be the best interface. A great example of this is the iPod. It does only a very few things, but it does them very well and simply.

It is tempting to take the easy way out and create a general interface for a particular task. In this case we are actually doing just that. In fact, it is easier to generate the interface to allow someone to customize hot keys than it is to come up with a set of hot keys that is really good. That's why we are doing this in the first place as it allows multiple different viewpoints of what make a good set of hot keys to exist within the same application.

However, in the case of the arrow keys we have a modal interface that allows different behavior depending on the mode based on an arrow key being depressed. These are all commands that affect navigation in a way that is intuitively associated with arrow keys.

Of course now we get into the realm of trying to predict what the customer wants. This is like trying to predict whether it will rain on Sunday or not. Pretty much whatever you decide is the desirable outcome will not be good.

The case of the arrow keys isn't nearly as compelling as many other cases. For example the tools for the blog I'm using now are quite limiting from a general word processing point of view. However, because they are so simple, even my wife can figure them out. Actually, she knows them far better than I as she has her own blog. In any case the point is that an interface is should be as simple as possible but no simpler.