Index: src/wp-admin/css/common.css
===================================================================
--- src/wp-admin/css/common.css	(revision 29332)
+++ src/wp-admin/css/common.css	(working copy)
@@ -218,6 +218,10 @@
 	padding-top: 1px;
 }
 
+body.modal-open {
+	overflow: hidden;
+}
+
 iframe,
 img {
 	border: 0;
Index: src/wp-admin/css/themes.css
===================================================================
--- src/wp-admin/css/themes.css	(revision 29332)
+++ src/wp-admin/css/themes.css	(working copy)
@@ -409,10 +409,6 @@
 	z-index: 10;
 }
 
-body.theme-overlay-open {
-	overflow: hidden;
-}
-
 .theme-overlay .theme-header {
 	position: absolute;
 	top: 0;
Index: src/wp-admin/js/theme.js
===================================================================
--- src/wp-admin/js/theme.js	(revision 29332)
+++ src/wp-admin/js/theme.js	(working copy)
@@ -701,7 +701,7 @@
 	// Performs the actions to effectively close
 	// the theme details overlay
 	closeOverlay: function() {
-		$( 'body' ).removeClass( 'theme-overlay-open' );
+		$( 'body' ).removeClass( 'modal-open' );
 		this.remove();
 		this.unbind();
 		this.trigger( 'theme:collapse' );
@@ -1000,7 +1000,7 @@
 
 		// Sets this.view to 'detail'
 		this.setView( 'detail' );
-		$( 'body' ).addClass( 'theme-overlay-open' );
+		$( 'body' ).addClass( 'modal-open' );
 
 		// Set up the theme details view
 		this.overlay = new themes.view.Details({
Index: src/wp-includes/js/media-views.js
===================================================================
--- src/wp-includes/js/media-views.js	(revision 29332)
+++ src/wp-includes/js/media-views.js	(working copy)
@@ -3228,6 +3228,9 @@
 				};
 			}
 
+			// Disable page scrolling.
+			$( 'body' ).addClass( 'modal-open' );
+
 			$el.show().find( '.media-modal-close' ).focus();
 			return this.propagate('open');
 		},
@@ -3243,6 +3246,9 @@
 				return this;
 			}
 
+			// Enable page scrolling.
+			$( 'body' ).removeClass( 'modal-open' );
+
 			// Hide modal and remove restricted media modal tab focus once it's closed
 			this.$el.hide().undelegate( 'keydown' );
 
Index: src/wp-includes/js/thickbox/thickbox.js
===================================================================
--- src/wp-includes/js/thickbox/thickbox.js	(revision 29332)
+++ src/wp-includes/js/thickbox/thickbox.js	(working copy)
@@ -46,6 +46,7 @@
 			if(document.getElementById("TB_overlay") === null){
 				jQuery("body").append("<div id='TB_overlay'></div><div id='TB_window'></div>");
 				jQuery("#TB_overlay").click(tb_remove);
+				jQuery( 'body' ).addClass( 'modal-open' );
 			}
 		}
 
@@ -264,6 +265,7 @@
  	jQuery("#TB_imageOff").unbind("click");
 	jQuery("#TB_closeWindowButton").unbind("click");
 	jQuery("#TB_window").fadeOut("fast",function(){jQuery('#TB_window,#TB_overlay,#TB_HideSelect').trigger("tb_unload").unbind().remove();});
+	jQuery( 'body' ).removeClass( 'modal-open' );
 	jQuery("#TB_load").remove();
 	if (typeof document.body.style.maxHeight == "undefined") {//if IE 6
 		jQuery("body","html").css({height: "auto", width: "auto"});