Simplify.

d3.v2.js

@@ -2421,8 +2421,8 @@ function d3_mousePoint(container, e) {
     return [point.x, point.y];
   }
   var rect = container.getBoundingClientRect();
-  return [e.pageX - rect.left - container.clientLeft - window.pageXOffset,
+  return [e.clientX - rect.left - container.clientLeft,
-      e.pageY - rect.top - container.clientTop - window.pageYOffset];
+      e.clientY - rect.top - container.clientTop];
 };
 d3.touches = function(container, touches) {
   if (arguments.length < 2) touches = d3.event.touches;

src/core/mouse.js

@@ -30,6 +30,6 @@ function d3_mousePoint(container, e) {
     return [point.x, point.y];
   }
   var rect = container.getBoundingClientRect();
-  return [e.pageX - rect.left - container.clientLeft - window.pageXOffset,
+  return [e.clientX - rect.left - container.clientLeft,
-      e.pageY - rect.top - container.clientTop - window.pageYOffset];
+      e.clientY - rect.top - container.clientTop];
 };