Multi-touch system and method for emulating modifier keys via fingertip chords

A multi-touch system is disclosed that recognizes simultaneous touchdown of four fingers on, above, or below the home row of keys as a modifier chord and applies modifiers such as Shift, Ctrl, or Alt to subsequent touch activity until none of the chord fingertips remain touching. Touches by the thumb of the modifier chord hand that occur before any modifiable typing or clicking activity cause the modifier chord to be canceled and reinterpreted as hand resting. The Shift modifier may be released temporarily during thumb keypresses that are intermixed with typing of capitalized characters. Distributing the modifier chord touches across different zones or key rows selects multiple modifiers. In an alternative embodiment, different modifiers can be selected with different arrangements of the fingers relative to one another within the chord, irrespective of absolute hand alignment with the…