- Patch #704182 by jide: use transparent PNG instead of opacity for overlay background to gain rendering performance.

modules/overlay/overlay-parent.css

@@ -4,10 +4,10 @@
  * ui-dialog overlay.
  */
 .ui-widget-overlay {
-  background-color: #222;
-  opacity: 0.85;
-  filter: alpha(opacity=85);
-  background-image: none;
+  opacity: 1;
+  filter: none;
+  /* Using a transparent png renders faster than using opacity */
+  background: transparent url(images/background.png) repeat;
 }
 
 body.overlay-autofit {
@@ -158,3 +158,13 @@ body.overlay-autofit {
 .overlay div.add-or-remove-shortcuts {
   padding-top: 0.9em;
 }
+
+/**
+ * IE 6 Fix.
+ *
+ * Use filter to support transparency in IE6 for the overlay background.
+ */
+* html .ui-widget-overlay {
+  filter: progid:DXImageTransform.Microsoft.AlphaImageLoader(src='modules/overlay/images/background.png', sizingMethod='scale');
+  background: none;
+}