prevent dimmed ocdialog div from scrolling

core/css/jquery.ocdialog.css

@@ -43,7 +43,7 @@
 	background-color: #000;
 	opacity: .20;filter:Alpha(Opacity=20);
 	z-index: 999;
-	position: absolute;
+	position: fixed;
 	top: 0; left: 0;
 	width: 100%; height: 100%;
 }