This scheme takes the horizontal or vertical position of a screen touch as a percentage of the total screen dimension, then moves the cursor to a similar position in the long list of options. Unfortunately, we found that the resolution of the touch-screen restricts accurate selection to lists smaller than the maximum number of pen positions that can be resolved. We also chose not to use this type of interface element because it demands continuous display feedback for each movement of the pen. Typically the feedback would be generated remotely, rather than by the tab itself, because the application generating the feedback is running elsewhere on the network. The contention that would result between pen events and continuous display updates would make poor use of the communication bandwidth.
Elision is based on k-ary search techniques.
The user selects the target item if it is displayed. Otherwise, selecting any ellipsis redraws the screen to show an expansion of the selected region of the list into 13 smaller portions as before. Elision is reasonably efficient. To select one item among one million, for example, requires no more than six selections. The mean word length in the American Heritage online dictionary, containing 84433 words, is 8.9 characters.