Index: src/wp-includes/js/comment-reply.js
===================================================================
--- src/wp-includes/js/comment-reply.js	(revision 35576)
+++ src/wp-includes/js/comment-reply.js	(working copy)
@@ -1,47 +1,92 @@
 var addComment = {
-	moveForm : function(commId, parentId, respondId, postId) {
-		var t = this, div, comm = t.I(commId), respond = t.I(respondId), cancel = t.I('cancel-comment-reply-link'), parent = t.I('comment_parent'), post = t.I('comment_post_ID');
+	moveForm: function( commId, parentId, respondId, postId ) {
+		var div, element, node, style, cssHidden,
+			t           = this,
+			comm        = t.I( commId ),
+			respond     = t.I( respondId ),
+			cancel      = t.I( 'cancel-comment-reply-link' ),
+			parent      = t.I( 'comment_parent' ),
+			post        = t.I( 'comment_post_ID' ),
+			commentForm = respond.getElementsByTagName( 'form' )[0];
 
-		if ( ! comm || ! respond || ! cancel || ! parent )
+		if ( ! comm || ! respond || ! cancel || ! parent || ! commentForm ) {
 			return;
+		}
 
 		t.respondId = respondId;
 		postId = postId || false;
 
-		if ( ! t.I('wp-temp-form-div') ) {
-			div = document.createElement('div');
+		if ( ! t.I( 'wp-temp-form-div' ) ) {
+			div = document.createElement( 'div' );
 			div.id = 'wp-temp-form-div';
 			div.style.display = 'none';
-			respond.parentNode.insertBefore(div, respond);
+			respond.parentNode.insertBefore( div, respond );
 		}
 
-		comm.parentNode.insertBefore(respond, comm.nextSibling);
-		if ( post && postId )
+		comm.parentNode.insertBefore( respond, comm.nextSibling );
+		if ( post && postId ) {
 			post.value = postId;
+		}
 		parent.value = parentId;
 		cancel.style.display = '';
 
 		cancel.onclick = function() {
-			var t = addComment, temp = t.I('wp-temp-form-div'), respond = t.I(t.respondId);
+			var t       = addComment,
+				temp    = t.I( 'wp-temp-form-div' ),
+				respond = t.I( t.respondId );
 
-			if ( ! temp || ! respond )
+			if ( ! temp || ! respond ) {
 				return;
+			}
 
-			t.I('comment_parent').value = '0';
-			temp.parentNode.insertBefore(respond, temp);
-			temp.parentNode.removeChild(temp);
+			t.I( 'comment_parent' ).value = '0';
+			temp.parentNode.insertBefore( respond, temp );
+			temp.parentNode.removeChild( temp );
 			this.style.display = 'none';
 			this.onclick = null;
 			return false;
 		};
 
-		try { t.I('comment').focus(); }
-		catch(e) {}
+		// Set initial focus to the first form focusable element.
+		try {
+			for ( var i = 0; i < commentForm.elements.length; i++ ) {
+				element = commentForm.elements[i];
 
+				// Skip form elements that are hidden, disabled, readonly.
+				if ( 'hidden' === element.type || element.hasAttribute( 'disabled' ) || element.hasAttribute( 'readonly' ) ) {
+					continue;
+				}
+
+				if ( 'getComputedStyle' in window ) {
+					node = element;
+					cssHidden = false;
+
+					while( node.parentNode ) {
+						style = window.getComputedStyle( node );
+
+						if ( style.display === 'none' || style.visibility === 'hidden' ) {
+							cssHidden = true;
+							break;
+						}
+
+						node = node.parentNode;
+					}
+
+					if ( cssHidden ) {
+						continue;
+					}
+				}
+
+				element.focus();
+				// Stop after the first focusable element.
+				break;
+			}
+		} catch( er ) {}
+
 		return false;
 	},
 
-	I : function(e) {
-		return document.getElementById(e);
+	I: function( id ) {
+		return document.getElementById( id );
 	}
 };