Index: wp-includes/js/thickbox/thickbox.css
===================================================================
--- wp-includes/js/thickbox/thickbox.css	(revision 17808)
+++ wp-includes/js/thickbox/thickbox.css	(working copy)
@@ -49,7 +49,7 @@
 	background: #ffffff;
 	z-index: 102;
 	color:#000000;
-	display:none;
+	visibility: hidden;
 	text-align:left;
 	top:50%;
 	left:50%;
Index: wp-includes/js/thickbox/thickbox.js
===================================================================
--- wp-includes/js/thickbox/thickbox.js	(revision 17808)
+++ wp-includes/js/thickbox/thickbox.js	(working copy)
@@ -269,7 +269,7 @@
 //helper functions below
 function tb_showIframe(){
 	jQuery("#TB_load").remove();
-	jQuery("#TB_window").css({display:"block"});
+	jQuery("#TB_window").css({display:"block", visibility: 'visible'});
 }
 
 function tb_remove() {