public int startDragPosition(MotionEvent ev) {
        return dragHandleHitPosition(ev);
    }
Get the position to start dragging based on the ACTION_DOWN
MotionEvent. This function simply calls
{@link #dragHandleHitPosition(MotionEvent)}. Override
to change drag handle behavior;
this function is called internally when an ACTION_DOWN
event is detected.

@param ev The ACTION_DOWN MotionEvent.

@return The list position to drag if a drag-init gesture is
detected; MISS if unsuccessful.
third_party/DragSortListView/src/com/mobeta/android/dslv/DragSortController.java