1. A computing system, comprising: a touch display; a gesture library including a shared modulate gesture and a plurality of different mode gestures, each mode gesture associated with a changeable parameter of the computing system, and the shared modulate gesture linkable with each mode gesture to indicate an amount to change the changeable parameter associated with that mode gesture; a touch-detection module to track a touch input directed to the touch display, the touch input beginning with a source engaging the touch display and continuing until the source disengages the touch display; a gesture-recognition module to select a selected mode gesture from the plurality of different mode gestures based on an initial portion of the touch input and to select the shared modulate gesture based on a subsequent portion of the touch input linked to the initial portion of the touch input; and a control module to change the changeable parameter associated with the selected mode gesture by an amount indicated by the shared modulate gesture.