diff --git a/platform/safari/vapi-background.js b/platform/safari/vapi-background.js
index 6769855fa..26b865923 100644
--- a/platform/safari/vapi-background.js
+++ b/platform/safari/vapi-background.js
@@ -190,21 +190,32 @@ vAPI.tabs = {
 vAPI.tabs.registerListeners = function() {
     var onNavigation = this.onNavigation;
 
-    this.onNavigation = function(e) {
-        // e.url is not present for local files or data URIs,
-        // or probably for those URLs which we don't have access to
-        if ( !e.target || !e.target.url ) {
+    safari.application.addEventListener('beforeNavigate', function(e) {
+        if ( !e.target || !e.target.url || e.target.url === 'about:blank' ) {
             return;
         }
-
+        var url = e.target.url, tabId = vAPI.tabs.getTabId(e.target);
+        if ( vAPI.tabs.popupCandidate ) {
+            var details = {
+                url: url,
+                tabId: tabId,
+                sourceTabId: vAPI.tabs.popupCandidate
+            };
+            vAPI.tabs.popupCandidate = false;
+            if ( vAPI.tabs.onPopup(details) ) {
+                e.preventDefault();
+                if ( vAPI.tabs.stack[details.sourceTabId] ) {
+                    vAPI.tabs.stack[details.sourceTabId].activate();
+                }
+                return;
+            }
+        }
         onNavigation({
+            url: url,
             frameId: 0,
-            tabId: vAPI.tabs.getTabId(e.target),
-            url: e.target.url
+            tabId: tabId
         });
-    };
-
-    safari.application.addEventListener('navigate', this.onNavigation, true);
+    }, true);
 
     // onClosed handled in the main tab-close event
     // onUpdated handled via monitoring the history.pushState on web-pages
@@ -577,27 +588,6 @@ vAPI.messaging.broadcast = function(message) {
 
 /******************************************************************************/
 
-safari.application.addEventListener('beforeNavigate', function(e) {
-    if ( !vAPI.tabs.popupCandidate || e.url === 'about:blank' ) {
-        return;
-    }
-
-    var details = {
-        url: e.url,
-        tabId: vAPI.tabs.getTabId(e.target),
-        sourceTabId: vAPI.tabs.popupCandidate
-    };
-
-    vAPI.tabs.popupCandidate = null;
-
-    if ( vAPI.tabs.onPopup(details) ) {
-        e.preventDefault();
-
-        if ( vAPI.tabs.stack[details.sourceTabId] ) {
-            vAPI.tabs.stack[details.sourceTabId].activate();
-        }
-    }
-}, true);
 
 /******************************************************************************/
 
diff --git a/platform/safari/vapi-client.js b/platform/safari/vapi-client.js
index 9adde80fd..958e8dc64 100644
--- a/platform/safari/vapi-client.js
+++ b/platform/safari/vapi-client.js
@@ -191,47 +191,31 @@ if ( location.protocol === 'safari-extension:' ) {
 
 /******************************************************************************/
 
-window.MutationObserver = window.MutationObserver || window.WebKitMutationObserver;
-
-if ( !window.MutationObserver ) {
-    // Dummy, minimalistic shim for older versions (<6)
-    // only supports node insertions, but currently we don't use it for anything else
-    window.MutationObserver = function(handler) {
-        this.observe = function(target) {
-            target.addEventListener('DOMNodeInserted', function(e) {
-                handler([{ addedNodes: [e.target] }]);
-            }, true);
-        };
-    };
-}
-
-/******************************************************************************/
-
 var beforeLoadEvent = document.createEvent('Event');
 beforeLoadEvent.initEvent('beforeload');
 
 /******************************************************************************/
 
 var frameId = window === window.top ? 0 : Date.now() % 1E5;
+var parentFrameId = frameId ? 0 : -1;
 var linkHelper = document.createElement('a');
 var onBeforeLoad = function(e, details) {
-    if ( e.url && e.url.slice(0, 5) === 'data:' ) {
+    if ( e.url && e.url.lastIndexOf('data:', 0) == 0 ) {
         return;
     }
 
     linkHelper.href = details ? details.url : e.url;
+    var url = linkHelper.href;
 
-    if ( linkHelper.protocol !== 'http:' && linkHelper.protocol !== 'https:' ) {
-        if ( !(details && details.type === 'popup') ) {
-            return;
-        }
+    if ( url.lastIndexOf('http:', 0) === -1 && url.lastIndexOf('https:', 0) === -1) {
+        return;
     }
 
     if ( details ) {
-        details.url = linkHelper.href;
+        details.url = url;
     } else {
         details = {
-            url: linkHelper.href
+            url: url
         };
 
         switch ( e.target.nodeName.toLowerCase() ) {
@@ -274,7 +258,7 @@ var onBeforeLoad = function(e, details) {
     // tabId is determined in the background script
     // details.tabId = null;
     details.frameId = frameId;
-    details.parentFrameId = frameId ? 0 : -1;
+    details.parentFrameId = parentFrameId;
     details.timeStamp = Date.now();
 
     var response = safari.self.tab.canLoad(e, details);
@@ -316,11 +300,10 @@ var onBeforeLoad = function(e, details) {
 document.addEventListener('beforeload', onBeforeLoad, true);
 
 /******************************************************************************/
-
 // block pop-ups, intercept xhr requests, and apply site patches
 var firstMutation = function() {
     document.removeEventListener('DOMSubtreeModified', firstMutation, true);
-    firstMutation = null;
+    firstMutation = false;
 
     var randEventName = uniqueId();
 
@@ -337,11 +320,10 @@ var firstMutation = function() {
     var tmpJS = document.createElement('script');
     var tmpScript = ['(function() {',
         'var block = function(u, t) {',
-            'var e = document.createEvent("CustomEvent"),',
-                'd = {url: u, type: t};',
-            'e.initCustomEvent("' + randEventName + '", false, false, d);',
+            'var e = new CustomEvent("' + randEventName +'",',
+                '{detail: {url: u, type: t}, bubbles: false});',
             'dispatchEvent(e);',
-            'return d.url === false;',
+            'return e.detail.url === false;',
         '}, wo = open, xo = XMLHttpRequest.prototype.open;',
         'open = function(u) {',
             'return block(u, "popup") ? null : wo.apply(this, arguments);',