Abstract: A touch-sensitive device accepts single-touch and multi-touch input representing gestures, and is able to changing a parameter of a gesture responsive to introduction or removal of a point of contact while the gesture is in progress. The operation associated with the gesture, such as a manipulation of an on-screen object, changes in a predictable manner if the user introduces or removes a contact point while the gesture is in progress. The overall nature of the operation being performed does not change, but a parameter of the operation can change. In various embodiments, each time a contact point is added or removed, the system and method of the present invention resets the relationship between the contact point locations and the operation being performed, in such a manner as to avoid or minimize discontinuities in the operation. In this manner, the invention avoids sudden or unpredictable changes to an object being manipulated.