Adding custom features to off-the-shelf computer programs such as Microsoft Word may soon be possible using a tool developed by U.S. scientists.

Researchers at the University of Washington have developed a method of modifying pixels on a computer screen to change the behaviour of a program, such as Microsoft Word or Apple iTunes. The display is overridden and users are able to customize how they interact with the program.

According to researchers, the tool, called Prefab, will allow users to customize their desktop in the same way people have been able to customize web pages. The research is outlined in the paper "Prefab: Implementing Advanced Behaviours Using Pixel-Based Reverse Engineering of Interface Structure."

For example, says co-author Morgan Dixon, to listen to music while working in Word without toggling between programs a user could potentially add a few iTunes buttons to the Word toolbar. "I'm using some program that I love," Dixon said in a release, "and I'm going to stick in some features from some other program that I love, so I have a more unified interface."

Prefab is able to alter the behaviour of blocks of code that make up the majority of computer displays, which include buttons, sliders, check boxes and drop-down menus.

The scientists hope that in addition to making the use of multiple computer programs more fluid and customized, their research will also help people with disabilities benefit from accessibility tools that make computer usage easier.

One such program the scientists cite is target-aware pointing, which can make interfaces easier to navigate for people suffering from Muscular Dystrophy, Parkinson's and other motor-control diseases. It uses a bubble cursor that illuminates buttons in its vicinity, allowing users to access more tools without having to click on them directly. Prefab would allow target-aware pointing to be integrated with various applications.

The method is described in a paper to be presented at the ACM Conference on Human Factors in Computing Systems taking place April 10-15 in Atlanta, Georgia.