Index: ui.draggable.ext.js
===================================================================
--- ui.draggable.ext.js	(revision 4585)
+++ ui.draggable.ext.js	(working copy)
@@ -90,6 +90,15 @@
 					$(document).width(),
 					($(document).height() || document.body.parentNode.scrollHeight)
 				];
+			} else if(o._containment == 'window' || o._containment == window) {
+				var leftAdjust = Math.max(document.documentElement.scrollLeft, document.body.scrollLeft);
+				var topAdjust = Math.max(document.documentElement.scrollTop, document.body.scrollTop);
+				o.containment = [
+					leftAdjust,
+					topAdjust,
+					$(window).width() + leftAdjust,
+					$(window).height() + topAdjust
+				];
 			} else { //I'm a node, so compute top/left/right/bottom
 
 				var ce = $(o._containment)[0];
@@ -112,10 +121,10 @@
 			var self = ui.instance;
 			
 			if(c.constructor == Array) {
-				if((ui.absolutePosition.left < c[0])) self.position.left = c[0] - (self.offset.left - self.clickOffset.left);
-				if((ui.absolutePosition.top < c[1])) self.position.top = c[1] - (self.offset.top - self.clickOffset.top);
-				if(ui.absolutePosition.left - c[2] + self.helperProportions.width >= 0) self.position.left = c[2] - (self.offset.left - self.clickOffset.left) - self.helperProportions.width;
-				if(ui.absolutePosition.top - c[3] + self.helperProportions.height >= 0) self.position.top = c[3] - (self.offset.top - self.clickOffset.top) - self.helperProportions.height;
+				if((ui.absolutePosition.left < c[0])) self.position.left = c[0] - (self.offset.left - self.clickOffset.left) - ( self.helperFixed ? Math.max(document.documentElement.scrollLeft, document.body.scrollLeft) : 0 );
+				if((ui.absolutePosition.top < c[1])) self.position.top = c[1] - (self.offset.top - self.clickOffset.top) - ( self.helperFixed ? Math.max(document.documentElement.scrollTop, document.body.scrollTop) : 0 );
+				if(ui.absolutePosition.left - c[2] + self.helperProportions.width >= 0) self.position.left = c[2] - (self.offset.left - self.clickOffset.left) - self.helperProportions.width - ( self.helperFixed ? Math.max(document.documentElement.scrollLeft, document.body.scrollLeft) : 0 );
+				if(ui.absolutePosition.top - c[3] + self.helperProportions.height >= 0) self.position.top = c[3] - (self.offset.top - self.clickOffset.top) - self.helperProportions.height - ( self.helperFixed ? Math.max(document.documentElement.scrollTop, document.body.scrollTop) : 0 );
 			} else {
 				if((ui.position.left < c.left)) self.position.left = c.left;
 				if((ui.position.top < c.top)) self.position.top = c.top;