Index: includes/AjaxFunctions.php
===================================================================
--- includes/AjaxFunctions.php	(revision 16398)
+++ includes/AjaxFunctions.php	(working copy)
@@ -131,4 +131,43 @@
 	return $response;
 }
 
+/**
+ * Called for AJAX watch/unwatch requests.
+ * @param $pageID Integer ID of the page to be watched/unwatched
+ * @param $watch String 'w' to watch, 'u' to unwatch
+ * @return String '<w#>' or '<u#>' on successful watch or unwatch, respectively, or '<err#>' on error (invalid XML in case we want to add HTML sometime)
+ */
+function wfAjaxWatch($pageID, $watch) {
+	if(wfReadOnly())
+		return '<err#>'; // redirect to action=(un)watch, which will display the database lock message
+
+	if(('w' !== $watch && 'u' !== $watch) || !is_numeric($pageID))
+		return '<err#>';
+	$watch = 'w' === $watch;
+	$pageID = intval($pageID);
+
+	$title = Title::newFromID($pageID);
+	if(!$title)
+		return '<err#>';
+	$article = new Article($title);
+	$watching = $title->userIsWatching();
+
+	if($watch) {
+		if(!$watching) {
+			$dbw =& wfGetDB(DB_MASTER);
+			$dbw->begin();
+			$article->doWatch();
+			$dbw->commit();
+		}
+	} else {
+		if($watching) {
+			$dbw =& wfGetDB(DB_MASTER);
+			$dbw->begin();
+			$article->doUnwatch();
+			$dbw->commit();
+		}
+	}
+
+	return $watch ? '<w#>' : '<u#>';
+}
 ?>
Index: includes/DefaultSettings.php
===================================================================
--- includes/DefaultSettings.php	(revision 16398)
+++ includes/DefaultSettings.php	(working copy)
@@ -2155,6 +2155,13 @@
 $wgAjaxSearch = false;
 
 /**
+ * Enable watching/unwatching pages using AJAX.
+ * Requires $wgUseAjax to be true too.
+ * Causes wfAjaxWatch to be added to $wgAjaxExportList
+ */
+$wgAjaxWatch = false;
+
+/**
  * List of Ajax-callable functions. 
  * Extensions acting as Ajax callbacks must register here
  */
Index: includes/OutputPage.php
===================================================================
--- includes/OutputPage.php	(revision 16398)
+++ includes/OutputPage.php	(working copy)
@@ -480,7 +480,7 @@
 	function output() {
 		global $wgUser, $wgOutputEncoding, $wgRequest;
 		global $wgContLanguageCode, $wgDebugRedirects, $wgMimeType;
-		global $wgJsMimeType, $wgStylePath, $wgUseAjax, $wgAjaxSearch, $wgScriptPath, $wgServer;
+		global $wgJsMimeType, $wgStylePath, $wgUseAjax, $wgAjaxSearch, $wgAjaxWatch, $wgScriptPath, $wgServer;
 
 		if( $this->mDoNothing ){
 			return;
@@ -491,11 +491,15 @@
 
 		if ( $wgUseAjax ) {
 			$this->addScript( "<script type=\"{$wgJsMimeType}\" src=\"{$wgStylePath}/common/ajax.js\"></script>\n" );
-		}
 
-		if ( $wgUseAjax && $wgAjaxSearch ) {
-			$this->addScript( "<script type=\"{$wgJsMimeType}\" src=\"{$wgStylePath}/common/ajaxsearch.js\"></script>\n" );
-			$this->addScript( "<script type=\"{$wgJsMimeType}\">hookEvent(\"load\", sajax_onload);</script>\n" );
+			if( $wgAjaxSearch ) {
+				$this->addScript( "<script type=\"{$wgJsMimeType}\" src=\"{$wgStylePath}/common/ajaxsearch.js\"></script>\n" );
+				$this->addScript( "<script type=\"{$wgJsMimeType}\">hookEvent(\"load\", sajax_onload);</script>\n" );
+			}
+
+			if( $wgAjaxWatch ) {
+				$this->addScript( "<script type=\"{$wgJsMimeType}\" src=\"{$wgStylePath}/common/ajaxwatch.js\"></script>\n" );
+			}
 		}
 
 		if ( '' != $this->mRedirect ) {
Index: includes/Setup.php
===================================================================
--- includes/Setup.php	(revision 16398)
+++ includes/Setup.php	(working copy)
@@ -169,6 +169,7 @@
 $wgPostCommitUpdateList = array();
 
 if ( $wgAjaxSearch ) $wgAjaxExportList[] = 'wfSajaxSearch';
+if ( $wgAjaxWatch ) $wgAjaxExportList[] = 'wfAjaxWatch';
 
 wfSeedRandom();
 
Index: includes/SkinTemplate.php
===================================================================
--- includes/SkinTemplate.php	(revision 16398)
+++ includes/SkinTemplate.php	(working copy)
@@ -571,7 +571,7 @@
 		}
 
 		$text = wfMsg( $message );
-		if ( $text == "&lt;$message&gt;" ) {
+		if ( wfEmptyMsg( $message, $text ) ) {
 			global $wgContLang;
 			$text = $wgContLang->getFormattedNsText( Namespace::getSubject( $title->getNamespace() ) );
 		}
@@ -1014,10 +1014,35 @@
 		// by checking for default message content
 		$msgKey = ucfirst($this->skinname).'.js';
 		$userJS = wfMsg($msgKey);
-		if ('&lt;'.$msgKey.'&gt;' != $userJS) {
+		if(!wfEmptyMsg($msgKey, $userJS)) {
 			$s .= $userJS;
 		}
 
+		global $wgUseAjax, $wgAjaxWatch;
+		if($wgUseAjax && $wgAjaxWatch) {
+			$s .= "\n\n/* AJAX (un)watch (see /skins/common/ajaxwatch.js) */\n";
+			$s .= "var wgAjaxWatch = {\n";
+			$first = true;
+			foreach( // array of [name of property in javascript] => [key for wfMsg], [option(s) for wfMsgExt]
+					array(
+						'watchMsg' => array('watch'),
+						'unwatchMsg' => array('unwatch'),
+						'watchingMsg' => array('watching'),
+						'unwatchingMsg' => array('unwatching'),
+						'addedWatchMsg' => array('addedwatchajaxtext', 'parse'),
+						'removedWatchMsg' => array('removedwatchajaxtext', 'parse')
+					) as $jsName => $msg) {
+				$msgKey = $msg[0];
+				array_shift($msg);
+				if(!$first)
+					$s .= ",\n";
+				else
+					$first = false;
+				$s .= "$jsName: '" . str_replace("'", "\\'", str_replace("\n", ' ', wfMsgExt($msgKey, $msg))) . "'";
+			}
+			$s .= "\n};";
+		}
+
 		wfProfileOut( $fname );
 		return $s;
 	}
Index: languages/MessagesEn.php
===================================================================
--- languages/MessagesEn.php	(revision 16398)
+++ languages/MessagesEn.php	(working copy)
@@ -1388,11 +1388,15 @@
 make it easier to pick out.
 
 If you want to remove the page from your watchlist later, click \"Unwatch\" in the sidebar.",
+'addedwatchajaxtext' => 'This page has been added to your [[{{ns:special}}:Watchlist|watchlist]].',
 'removedwatch'		=> 'Removed from watchlist',
 'removedwatchtext' 	=> "The page \"[[:$1]]\" has been removed from your watchlist.",
+'removedwatchajaxtext' => 'This page has been removed from your watchlist.',
 'watch' => 'Watch',
+'watching' => 'Watching...',
 'watchthispage'		=> 'Watch this page',
 'unwatch' => 'Unwatch',
+'unwatching' => 'Unwatching...',
 'unwatchthispage' 	=> 'Stop watching',
 'notanarticle'		=> 'Not a content page',
 'watchnochange' 	=> 'None of your watched items was edited in the time period displayed.',
Index: skins/common/ajaxwatch.js
===================================================================
--- skins/common/ajaxwatch.js	(revision 0)
+++ skins/common/ajaxwatch.js	(revision 0)
@@ -0,0 +1,135 @@
+// dependencies:
+// * ajax.js: sajax_init_object(), sajax_do_call()
+// * wikibits.js: changeText(), akeyttfor(), hookEvent()
+
+// wgAjaxWatch should have been initialized in the generated js
+if(typeof wgAjaxWatch == "undefined" || !wgAjaxWatch) {
+	var wgAjaxWatch = {
+		watchMsg: "Watch",
+		unwatchMsg: "Unwatch",
+		watchingMsg: "Watching...",
+		unwatchingMsg: "Unwatching...",
+		addedWatchMsg: "This page has been added to your watchlist.",
+		removedWatchMsg: "This page has been removed from your watchlist."
+	};
+}
+
+wgAjaxWatch.supported = true; // supported on current page and by browser
+wgAjaxWatch.watching = false; // currently watching page
+wgAjaxWatch.inprogress = false; // ajax request in progress
+wgAjaxWatch.timeoutID = null; // see wgAjaxWatch.ajaxCall
+wgAjaxWatch.watchLink = null; // "watch"/"unwatch" link
+wgAjaxWatch.oldHref = null; // url for action=watch/action=unwatch
+
+wgAjaxWatch.setLinkText = function(newText) {
+	changeText(wgAjaxWatch.watchLink, newText);
+}
+
+wgAjaxWatch.setLinkID = function(newId) {
+	wgAjaxWatch.watchLink.id = newId;
+	akeyttfor(newId); // update tooltip
+}
+
+wgAjaxWatch.ajaxCall = function() {
+	if(!wgAjaxWatch.supported || wgAjaxWatch.inprogress)
+		return;
+	wgAjaxWatch.inprogress = true;
+	wgAjaxWatch.setLinkText(wgAjaxWatch.watching ? wgAjaxWatch.unwatchingMsg : wgAjaxWatch.watchingMsg);
+	sajax_do_call("wfAjaxWatch", [wgArticleId, (wgAjaxWatch.watching ? "u" : "w")], wgAjaxWatch.processResult);
+	// if the request isn't done in 10 seconds, allow user to try again
+	wgAjaxWatch.timeoutID = window.setTimeout(function() { wgAjaxWatch.inprogress = false; }, 10000);
+	return;
+};
+
+wgAjaxWatch.processResult = function(request) {
+	if(!wgAjaxWatch.supported)
+		return;
+	var response = request.responseText;
+	if(response == "<err#>") {
+		window.location.href = wgAjaxWatch.oldHref;
+		return;
+	} else if(response == "<w#>") {
+		wgAjaxWatch.watching = true;
+		wgAjaxWatch.setLinkText(wgAjaxWatch.unwatchMsg);
+		wgAjaxWatch.setLinkID("ca-unwatch");
+		wgAjaxWatch.oldHref = wgAjaxWatch.oldHref.replace(/action=watch/, "action=unwatch");
+		wfDisplayUserMsg("ajaxwatch", wgAjaxWatch.addedWatchMsg);
+	} else if(response == "<u#>") {
+		wgAjaxWatch.watching = false;
+		wgAjaxWatch.setLinkText(wgAjaxWatch.watchMsg);
+		wgAjaxWatch.setLinkID("ca-watch");
+		wgAjaxWatch.oldHref = wgAjaxWatch.oldHref.replace(/action=unwatch/, "action=watch");
+		wfDisplayUserMsg("ajaxwatch", wgAjaxWatch.removedWatchMsg);
+	}
+	wgAjaxWatch.inprogress = false;
+	if(wgAjaxWatch.timeoutID)
+		window.clearTimeout(wgAjaxWatch.timeoutID);
+	return;
+};
+
+wgAjaxWatch.onLoad = function() {
+	var x = document.getElementById("ca-unwatch");
+	if(x) {
+		wgAjaxWatch.watching = true;
+	} else {
+		wgAjaxWatch.watching = false;
+		x = document.getElementById("ca-watch");
+		if(!x) {
+			wgAjaxWatch.supported = false;
+			return;
+		}
+	}
+
+	if(!wfSupportsAjax()) {
+		wgAjaxWatch.supported = false;
+		return;
+	}
+
+	wgAjaxWatch.watchLink = x.firstChild;
+
+	wgAjaxWatch.oldHref = wgAjaxWatch.watchLink.getAttribute("href");
+	wgAjaxWatch.watchLink.setAttribute("href", "javascript:wgAjaxWatch.ajaxCall()");
+	return;
+};
+
+hookEvent("load", wgAjaxWatch.onLoad);
+
+/**
+ * Displays a message to the user. In old browsers, this falls back
+ * to display an alert() box.
+ * @param String msgName the name of the message; messages with the
+ *    same name will overwrite each other
+ * @param String text the content of the message
+ */
+function wfDisplayUserMsg(msgName, msgText) {
+	msgName = "msg-" + msgName.replace(/ /g, "-"); // avoid collisions
+	var msg = document.getElementById(msgName);
+	if(msg) {
+		msg.innerHTML = msgText;
+		return;
+	}
+
+	var contentsub = document.getElementById("contentSub2");
+	if(!contentsub)
+		contentsub = document.getElementById("contentSub");
+	if(!contentsub || !document.createElement)
+		alert(msgText);
+
+	msg = document.createElement("div");
+	msg.id = msgName;
+	msg.className = "usermessage";
+	msg.innerHTML = msgText;
+
+	contentsub.parentNode.insertBefore(msg, contentsub.nextSibling);
+	return;
+}
+
+/**
+ * @return boolean whether the browser supports XMLHttpRequest
+ */
+function wfSupportsAjax() {
+	var request = sajax_init_object();
+	var supportsAjax = request ? true : false;
+	delete request;
+	return supportsAjax;
+}
Index: skins/common/wikibits.js
===================================================================
--- skins/common/wikibits.js	(revision 16398)
+++ skins/common/wikibits.js	(working copy)
@@ -459,48 +459,78 @@
 		txtarea.caretPos = document.selection.createRange().duplicate();
 }
 
-function akeytt() {
-	if (typeof ta == "undefined" || !ta)
-		return;
-	var pref = 'alt-';
+/**
+ * @return {String} browser-specific access key prefix
+ */
+function akeyprefix() {
 	if (is_safari || navigator.userAgent.toLowerCase().indexOf('mac') + 1
 		|| navigator.userAgent.toLowerCase().indexOf('konqueror') + 1 )
-		pref = 'control-';
+		return 'control-';
 	if (is_opera)
-		pref = 'shift-esc-';
+		return 'shift-esc-';
+	return 'alt-';
+}
 
-	for (var id in ta) {
-		var n = document.getElementById(id);
-		if (n) {
-			var a = null;
-			var ak = '';
-			// Are we putting accesskey in it
-			if (ta[id][0].length > 0) {
-				// Is this object a object? If not assume it's the next child.
+/**
+ * Sets access key and tooltip for element with specified id.
+ * @param {String} id id of the element
+ * @see #akeytt
+ * @see #akeyttfor2
+ */
+function akeyttfor(id) {
+	akeyttfor2(id, akeyprefix());
+}
 
-				if (n.nodeName.toLowerCase() == "a") {
-					a = n;
-				} else {
-					a = n.childNodes[0];
-				}
+/**
+ * Same as akeyttfor, but can be more efficient if access key prefix
+ * is used repeatedly.
+ * @param {String} id id of the element
+ * @param {String} akeypref access key prefix
+ * @see #akeytt
+ * @see #akeyttfor
+ */
+function akeyttfor2(id, akeypref) {
+	if (typeof ta == "undefined" || !ta)
+		return false;
 
-				if (a) {
-					a.accessKey = ta[id][0];
-					ak = ' ['+pref+ta[id][0]+']';
-				}
-			} else {
-				// We don't care what type the object is when assigning tooltip
-				a = n;
-				ak = '';
-			}
+	var n = document.getElementById(id);
+	if (!n)
+		return false;
 
-			if (a) {
-				a.title = ta[id][1]+ak;
-			}
+	var a = null;
+	var ak = '';
+	// Are we putting access key on it?
+	if (ta[id][0].length > 0) {
+		// Is this object a link? If not assume it's the next child.
+		a = n.nodeName.toLowerCase() == "a" ? n : n.firstChild;
+		if (a) {
+			a.accessKey = ta[id][0];
+			ak = ' [' + akeypref + ta[id][0] + ']';
 		}
+	} else {
+		// We don't care what type the object is when assigning tooltip
+		a = n;
+		ak = '';
 	}
+
+	if (a) {
+		a.title = ta[id][1] + ak;
+	}
 }
 
+/**
+ * Sets access keys and tooltips for all elements in the "ta" object.
+ * @see #akeyttfor
+ */
+function akeytt() {
+	if (typeof ta == "undefined" || !ta)
+		return false;
+	var pref = akeyprefix();
+	for (var id in ta)
+		akeyttfor2(id, pref);
+	return true;
+}
+
 function setupRightClickEdit() {
 	if (document.getElementsByTagName) {
 		var divs = document.getElementsByTagName('div');