--- a/embedding/browser/nsDocShellTreeOwner.cpp
+++ b/embedding/browser/nsDocShellTreeOwner.cpp
@@ -1130,17 +1130,17 @@ NS_IMPL_ISUPPORTS(ChromeTooltipListener,
 // ChromeTooltipListener ctor
 //
 
 ChromeTooltipListener::ChromeTooltipListener(nsWebBrowser* inBrowser,
                                              nsIWebBrowserChrome* inChrome) 
   : mWebBrowser(inBrowser), mWebBrowserChrome(inChrome),
      mTooltipListenerInstalled(false),
      mMouseClientX(0), mMouseClientY(0),
-     mShowingTooltip(false)
+     mShowingTooltip(false), mTooltipShownOnce(false)
 {
   mTooltipTextProvider = do_GetService(NS_TOOLTIPTEXTPROVIDER_CONTRACTID);
   if (!mTooltipTextProvider) {
     nsISupports *pProvider = (nsISupports *) new DefaultTooltipTextProvider;
     mTooltipTextProvider = do_QueryInterface(pProvider);
   }
 } // ctor
 
@@ -1265,21 +1265,27 @@ ChromeTooltipListener::RemoveTooltipList
 
 NS_IMETHODIMP
 ChromeTooltipListener::HandleEvent(nsIDOMEvent* aEvent)
 {
   nsAutoString eventType;
   aEvent->GetType(eventType);
 
   if (eventType.EqualsLiteral("keydown") ||
-      eventType.EqualsLiteral("mousedown") ||
-      eventType.EqualsLiteral("mouseout"))
+      eventType.EqualsLiteral("mousedown")) {
     return HideTooltip();
-  if (eventType.EqualsLiteral("mousemove"))
+  }
+  else if (eventType.EqualsLiteral("mouseout")) {
+    // Reset flag so that tooltip will display on the next MouseMove
+    mTooltipShownOnce = false;
+    return HideTooltip();
+  }
+  else if (eventType.EqualsLiteral("mousemove")) {
     return MouseMove(aEvent);
+  }
 
   NS_ERROR("Unexpected event type");
   return NS_OK;
 }
 
 //
 // MouseMove
 //
@@ -1297,45 +1303,53 @@ ChromeTooltipListener::MouseMove(nsIDOME
   // timer callback. On win32, we'll get a MouseMove event even when a popup goes away --
   // even when the mouse doesn't change position! To get around this, we make sure the
   // mouse has really moved before proceeding.
   int32_t newMouseX, newMouseY;
   mouseEvent->GetClientX(&newMouseX);
   mouseEvent->GetClientY(&newMouseY);
   if ( mMouseClientX == newMouseX && mMouseClientY == newMouseY )
     return NS_OK;
+
+  // Filter out minor mouse movements.
+  if (mShowingTooltip &&
+      (abs(mMouseClientX - newMouseX) <= kTooltipMouseMoveTolerance) &&
+      (abs(mMouseClientY - newMouseY) <= kTooltipMouseMoveTolerance))
+    return NS_OK;
+
   mMouseClientX = newMouseX; mMouseClientY = newMouseY;
   mouseEvent->GetScreenX(&mMouseScreenX);
   mouseEvent->GetScreenY(&mMouseScreenY);
 
-  // We want to close the tip if it is being displayed and the mouse moves. Recall 
-  // that |mShowingTooltip| is set when the popup is showing. Furthermore, as the mouse
-  // moves, we want to make sure we reset the timer to show it, so that the delay
-  // is from when the mouse stops moving, not when it enters the element.
-  if ( mShowingTooltip )
-    return HideTooltip();
-  if ( mTooltipTimer )
+  if ( mTooltipTimer ) {
     mTooltipTimer->Cancel();
+  }
 
-  mTooltipTimer = do_CreateInstance("@mozilla.org/timer;1");
-  if ( mTooltipTimer ) {
-    nsCOMPtr<EventTarget> eventTarget = aMouseEvent->InternalDOMEvent()->GetTarget();
-    if ( eventTarget )
-      mPossibleTooltipNode = do_QueryInterface(eventTarget);
-    if ( mPossibleTooltipNode ) {
-      nsresult rv =
-        mTooltipTimer->InitWithFuncCallback(sTooltipCallback, this,
-          LookAndFeel::GetInt(LookAndFeel::eIntID_TooltipDelay, 500),
-          nsITimer::TYPE_ONE_SHOT);
-      if (NS_FAILED(rv))
-        mPossibleTooltipNode = nullptr;
+  if (!mShowingTooltip && !mTooltipShownOnce) {
+    mTooltipTimer = do_CreateInstance("@mozilla.org/timer;1");
+    if ( mTooltipTimer ) {
+      nsCOMPtr<EventTarget> eventTarget = aMouseEvent->InternalDOMEvent()->GetTarget();
+      if ( eventTarget )
+        mPossibleTooltipNode = do_QueryInterface(eventTarget);
+      if ( mPossibleTooltipNode ) {
+        nsresult rv =
+          mTooltipTimer->InitWithFuncCallback(sTooltipCallback, this,
+            LookAndFeel::GetInt(LookAndFeel::eIntID_TooltipDelay, 500),
+            nsITimer::TYPE_ONE_SHOT);
+        if (NS_FAILED(rv))
+          mPossibleTooltipNode = nullptr;
+      }
     }
+    else
+      NS_WARNING ( "Could not create a timer for tooltip tracking" );
   }
-  else
-    NS_WARNING ( "Could not create a timer for tooltip tracking" );
+  else {
+    mTooltipShownOnce = true;
+    return HideTooltip();
+  }
 
   return NS_OK;
 
 } // MouseMove
 
 
 //
 // ShowTooltip
@@ -1374,20 +1388,16 @@ ChromeTooltipListener::HideTooltip()
   
   // shut down the relevant timers
   if ( mTooltipTimer ) {
     mTooltipTimer->Cancel();
     mTooltipTimer = nullptr;
     // release tooltip target
     mPossibleTooltipNode = nullptr;
   }
-  if ( mAutoHideTimer ) {
-    mAutoHideTimer->Cancel();
-    mAutoHideTimer = nullptr;
-  }
 
   // if we're showing the tip, tell the chrome to hide it
   if ( mShowingTooltip ) {
     nsCOMPtr<nsITooltipListener> tooltipListener ( do_QueryInterface(mWebBrowserChrome) );
     if ( tooltipListener ) {
       rv = tooltipListener->OnHideTooltip ( );
       if ( NS_SUCCEEDED(rv) )
         mShowingTooltip = false;
@@ -1456,72 +1466,30 @@ ChromeTooltipListener::sTooltipCallback(
     if (self->mTooltipTextProvider) {
       bool textFound = false;
 
       self->mTooltipTextProvider->GetNodeText(
           self->mPossibleTooltipNode, getter_Copies(tooltipText), &textFound);
       
       if (textFound) {
         nsString tipText(tooltipText);
-        self->CreateAutoHideTimer();
         nsIntPoint screenDot = widget->WidgetToScreenOffset();
         self->ShowTooltip (self->mMouseScreenX - screenDot.x,
                            self->mMouseScreenY - screenDot.y,
                            tipText);
       }
     }
     
     // release tooltip target if there is one, NO MATTER WHAT
     self->mPossibleTooltipNode = nullptr;
   } // if "self" data valid
   
 } // sTooltipCallback
 
 
-//
-// CreateAutoHideTimer
-//
-// Create a new timer to see if we should auto-hide. It's ok if this fails.
-//
-void
-ChromeTooltipListener::CreateAutoHideTimer()
-{
-  // just to be anal (er, safe)
-  if ( mAutoHideTimer ) {
-    mAutoHideTimer->Cancel();
-    mAutoHideTimer = nullptr;
-  }
-  
-  mAutoHideTimer = do_CreateInstance("@mozilla.org/timer;1");
-  if ( mAutoHideTimer )
-    mAutoHideTimer->InitWithFuncCallback(sAutoHideCallback, this, kTooltipAutoHideTime, 
-                                         nsITimer::TYPE_ONE_SHOT);
-
-} // CreateAutoHideTimer
-
-
-//
-// sAutoHideCallback
-//
-// This fires after a tooltip has been open for a certain length of time. Just tell
-// the listener to close the popup. We don't have to worry, because HideTooltip() can
-// be called multiple times, even if the tip has already been closed.
-//
-void
-ChromeTooltipListener::sAutoHideCallback(nsITimer *aTimer, void* aListener)
-{
-  ChromeTooltipListener* self = static_cast<ChromeTooltipListener*>(aListener);
-  if ( self )
-    self->HideTooltip();
-
-  // NOTE: |aTimer| and |self->mAutoHideTimer| are invalid after calling ClosePopup();
-  
-} // sAutoHideCallback
-
-
 NS_IMPL_ISUPPORTS(ChromeContextMenuListener, nsIDOMEventListener)
 
 
 //
 // ChromeTooltipListener ctor
 //
 ChromeContextMenuListener::ChromeContextMenuListener(nsWebBrowser* inBrowser, nsIWebBrowserChrome* inChrome ) 
   : mContextMenuListenerInstalled(false),

--- a/embedding/browser/nsDocShellTreeOwner.h
+++ b/embedding/browser/nsDocShellTreeOwner.h
@@ -161,17 +161,18 @@ public:
     // the embedding chrome implements.
   NS_IMETHOD AddChromeListeners();
   NS_IMETHOD RemoveChromeListeners();
 
 private:
 
     // various delays for tooltips
   enum {
-    kTooltipAutoHideTime = 5000        // 5000ms = 5 seconds
+    kTooltipAutoHideTime = 5000,       // 5000ms = 5 seconds
+    kTooltipMouseMoveTolerance = 7     // 7 pixel tolerance for mousemove event
   };
 
   NS_IMETHOD AddTooltipListener();
   NS_IMETHOD RemoveTooltipListener();
 
   NS_IMETHOD ShowTooltip ( int32_t inXCoords, int32_t inYCoords, const nsAString & inTipText ) ;
   NS_IMETHOD HideTooltip ( ) ;
 
@@ -187,21 +188,17 @@ private:
 
   bool mTooltipListenerInstalled;
 
   nsCOMPtr<nsITimer> mTooltipTimer;
   static void sTooltipCallback ( nsITimer* aTimer, void* aListener ) ;
   int32_t mMouseClientX, mMouseClientY;       // mouse coordinates for last mousemove event we saw
   int32_t mMouseScreenX, mMouseScreenY;       // mouse coordinates for tooltip event
   bool mShowingTooltip;
-
-    // a timer for auto-hiding the tooltip after a certain delay
-  nsCOMPtr<nsITimer> mAutoHideTimer;
-  static void sAutoHideCallback ( nsITimer* aTimer, void* aListener ) ;
-  void CreateAutoHideTimer ( ) ;
+  bool mTooltipShownOnce;
 
     // The node hovered over that fired the timer. This may turn into the node that
     // triggered the tooltip, but only if the timer ever gets around to firing.
     // This is a strong reference, because the tooltip content can be destroyed while we're
     // waiting for the tooltip to pup up, and we need to detect that.
     // It's set only when the tooltip timer is created and launched. The timer must
     // either fire or be cancelled (or possibly released?), and we release this
     // reference in each of those cases. So we don't leak.