diff --git a/embedding/components/windowwatcher/src/nsWindowWatcher.cpp b/embedding/components/windowwatcher/src/nsWindowWatcher.cpp
index 051ff99d032..a8db18c612b 100644
--- a/embedding/components/windowwatcher/src/nsWindowWatcher.cpp
+++ b/embedding/components/windowwatcher/src/nsWindowWatcher.cpp
@@ -609,13 +609,12 @@ nsWindowWatcher::OpenWindowJS(nsIDOMWindow *aParent,
 
     if (weAreModal) {
       rv = queueGuard.Push();
-      if (NS_FAILED(rv))
-        return rv;
-
-      windowIsModal = PR_TRUE;
-      // in case we added this because weAreModal
-      chromeFlags |= nsIWebBrowserChrome::CHROME_MODAL |
-                     nsIWebBrowserChrome::CHROME_DEPENDENT;
+      if (NS_SUCCEEDED(rv)) {
+        windowIsModal = PR_TRUE;
+        // in case we added this because weAreModal
+        chromeFlags |= nsIWebBrowserChrome::CHROME_MODAL |
+          nsIWebBrowserChrome::CHROME_DEPENDENT;
+      }
     }
 
     NS_ASSERTION(mWindowCreator,
diff --git a/xpcom/threads/nsEventQueue.cpp b/xpcom/threads/nsEventQueue.cpp
index 0d9a29c3bec..6d375e7eef8 100644
--- a/xpcom/threads/nsEventQueue.cpp
+++ b/xpcom/threads/nsEventQueue.cpp
@@ -62,8 +62,6 @@ static PLEventQueue *gEventQueueLogQueue = 0;
 static PRThread *gEventQueueLogThread = 0;
 #endif
 
-#define MAX_EVENTQUEUE_NESTING_DEPTH 12
-
 // in a real system, these would be members in a header class...
 static const char gActivatedNotification[] = "nsIEventQueueActivated";
 static const char gDestroyedNotification[] = "nsIEventQueueDestroyed";
@@ -541,32 +539,26 @@ nsEventQueueImpl::AppendQueue(nsIEventQueue *aQueue)
 */
   rv = NS_ERROR_NO_INTERFACE;
 
-  GetYoungest(getter_AddRefs(end));
-  nsCOMPtr<nsPIEventQueueChain> endChain(do_QueryInterface(end));
-  
-  // (be careful doing this outside nsEventQueueService's mEventQMonitor)
-
-  if (endChain) {
-    int depth = 0;
-    nsCOMPtr<nsPIEventQueueChain> chain = endChain;
-    while (chain) {
-      nsCOMPtr<nsIEventQueue> q;
-      chain->GetElder(getter_AddRefs(q));
-      chain = do_QueryInterface(q);
-      ++depth;
-      if (depth > MAX_EVENTQUEUE_NESTING_DEPTH)
-        return NS_ERROR_FAILURE;
-    }
-  
 #ifdef NS_DEBUG
-    if (depth > 5) {
-      char warning[80];
-      PR_snprintf(warning, sizeof(warning),
-        "event queue chain length is %d. this is almost certainly a leak.", depth);
-      NS_WARNING(warning);
-    }
+  int depth = 0;
+  nsEventQueueImpl *next = this;
+  while (next && depth < 100) {
+    next = NS_STATIC_CAST(nsEventQueueImpl *, next->mYoungerQueue);
+    ++depth;
+  }
+  if (depth > 5) {
+    char warning[80];
+    PR_snprintf(warning, sizeof(warning),
+      "event queue chain length is %d. this is almost certainly a leak.", depth);
+    NS_WARNING(warning);
+  }
 #endif
 
+  // (be careful doing this outside nsEventQueueService's mEventQMonitor)
+
+  GetYoungest(getter_AddRefs(end));
+  nsCOMPtr<nsPIEventQueueChain> endChain(do_QueryInterface(end));
+  if (endChain) {
     endChain->SetYounger(queueChain);
     queueChain->SetElder(endChain);
     rv = NS_OK;
@@ -651,7 +643,7 @@ nsEventQueueImpl::GetYounger(nsIEventQueue **aQueue)
     *aQueue = nsnull;
     return NS_OK;
   }
-  return CallQueryInterface(mYoungerQueue, aQueue);
+  return mYoungerQueue->QueryInterface(NS_GET_IID(nsIEventQueue), (void**)&aQueue);
 }
 
 NS_IMETHODIMP
@@ -661,7 +653,7 @@ nsEventQueueImpl::GetElder(nsIEventQueue **aQueue)
     *aQueue = nsnull;
     return NS_OK;
   }
-  return CallQueryInterface(mElderQueue, aQueue);
+  return mElderQueue->QueryInterface(NS_GET_IID(nsIEventQueue), (void**)&aQueue);
 }
 
 NS_IMETHODIMP
diff --git a/xpcom/threads/nsEventQueueService.cpp b/xpcom/threads/nsEventQueueService.cpp
index 6551e7c03e6..6b16002e28e 100644
--- a/xpcom/threads/nsEventQueueService.cpp
+++ b/xpcom/threads/nsEventQueueService.cpp
@@ -296,24 +296,20 @@ nsEventQueueServiceImpl::PushThreadEventQueue(nsIEventQueue **aNewQueue)
       mEventQTable.Put(currentThread, newQueue);
     }
 
-    // append to the event queue chain -- QI the queue in the hash table
-    nsCOMPtr<nsPIEventQueueChain> ourChain(do_QueryInterface(queue));
+      // append to the event queue chain -- QI the queue in the hash table
+      nsCOMPtr<nsPIEventQueueChain> ourChain(do_QueryInterface(queue));
     if (ourChain)
-      rv = ourChain->AppendQueue(newQueue); // append new queue to it
+      ourChain->AppendQueue(newQueue); // append new queue to it
 
-    if (NS_FAILED(rv)) {
-      NS_RELEASE(newQueue);
-    } else {
-      *aNewQueue = newQueue;
+    *aNewQueue = newQueue;
 
 #if defined(PR_LOGGING) && defined(DEBUG_danm)
-      PLEventQueue *equeue;
-      (*aNewQueue)->GetPLEventQueue(&equeue);
-      PR_LOG(gEventQueueLog, PR_LOG_DEBUG,
-             ("EventQueue: Service push queue [queue=%lx]",(long)equeue));
-      ++gEventQueueLogCount;
+    PLEventQueue *equeue;
+    (*aNewQueue)->GetPLEventQueue(&equeue);
+    PR_LOG(gEventQueueLog, PR_LOG_DEBUG,
+           ("EventQueue: Service push queue [queue=%lx]",(long)equeue));
+    ++gEventQueueLogCount;
 #endif
-    }
   }
 
   // Release the EventQ lock...