Index: src/wp-includes/js/wp-lists.js
===================================================================
--- src/wp-includes/js/wp-lists.js	(revision 37848)
+++ src/wp-includes/js/wp-lists.js	(working copy)
@@ -160,6 +160,10 @@
 	 * @return {boolean}
 	 */
 	ajaxDel: function( e, s ) {
+		// Return if there is already an AJAX request in progress
+		if ( wpList.xhr && wpList.xhr.readyState !== 4 )
+			return false;
+
 		e = $(e);
 		s = s || {};
 		var list = this, data = wpList.parseData(e,'delete'), element, res, rres;
@@ -225,11 +229,15 @@
 			}
 		};
 
-		$.ajax( s );
+		wpList.xhr = $.ajax( s );
 		return false;
 	},
 
 	ajaxDim: function( e, s ) {
+		// Return if there is already an AJAX request in progress
+		if ( wpList.xhr && wpList.xhr.readyState !== 4 )
+			return false;
+
 		if ( $(e).parent().css('display') == 'none' ) // Prevent hidden links from being clicked by hotkeys
 			return false;
 
@@ -326,7 +334,7 @@
 			}
 		};
 
-		$.ajax( s );
+		wpList.xhr = $.ajax( s );
 		return false;
 	},