8. The method of claim 1 , further comprising: in response to determining that the initial portion of the gesture is detected at a location corresponding to a second region of the electronic document, selecting a second dynamic disambiguation threshold used to determine whether to perform navigation or annotation.
8. The method of claim 1 , further comprising: in response to determining that the initial portion of the gesture is detected at a location corresponding to a second region of the electronic document, selecting a second dynamic disambiguation threshold used to determine whether to perform navigation or annotation. 9. The method of claim 8 , wherein the second dynamic disambiguation threshold is selected such that a range of values corresponding to an annotation operation is an empty set, the method further comprising: in response to detecting movement of the contact, performing a navigation operation.