Index: src/core.js
===================================================================
--- src/core.js	(revision 3977)
+++ src/core.js	(working copy)
@@ -764,7 +764,7 @@
 
 			// Revert the padding and border widths to get the
 			// correct height/width values
-			jQuery.each([ "Top", "Bottom", "Right", "Left" ], function(){
+			jQuery.each(name == "width" ? [ "Right", "Left" ] : [ "Top", "Bottom" ], function(){
 				old[ "padding" + this ] = 0;
 				old[ "border" + this + "Width" ] = 0;
 			});