Fixing bug 371200. Make us have only one pref observer for browser.chrome.toolbar_tips rather than having every single XUL tooltip listener listen for changes to the pref only to update a global variable. r+sr=jonas@sicking.cc

layout/xul/base/src/nsXULTooltipListener.cpp

@@ -76,16 +76,26 @@ nsXULTooltipListener::nsXULTooltipListener()
   , mLastTreeRow(-1)
 #endif
 {
+  if (sTooltipListenerCount++ == 0) {
+    // register the callback so we get notified of updates
+    nsContentUtils::RegisterPrefCallback("browser.chrome.toolbar_tips",
+                                         ToolbarTipsPrefChanged, this);
+
+    // Call the pref callback to initialize our state.
+    ToolbarTipsPrefChanged("browser.chrome.toolbar_tips", nsnull);
+  }
 }
 
 nsXULTooltipListener::~nsXULTooltipListener()
 {
   HideTooltip();
 
+  if (--sTooltipListenerCount == 0) {
     // Unregister our pref observer
     nsContentUtils::UnregisterPrefCallback("browser.chrome.toolbar_tips",
                                            ToolbarTipsPrefChanged, this);
   }
+}
 
 NS_IMPL_ADDREF(nsXULTooltipListener)
 NS_IMPL_RELEASE(nsXULTooltipListener)
@@ -272,6 +282,7 @@ nsXULTooltipListener::PopupHiding(nsIDOMEvent* aEvent)
 //// nsXULTooltipListener
 
 PRBool nsXULTooltipListener::sShowTooltips = PR_FALSE;
+PRUint32 nsXULTooltipListener::sTooltipListenerCount = 0;
 
 // XXX: This could all be done in the ctor.
 nsresult
@@ -286,14 +297,6 @@ nsXULTooltipListener::Init(nsIContent* aSourceNode)
   mIsSourceTree = mSourceNode->Tag() == nsGkAtoms::treechildren;
 #endif
 
-  // get the initial value of the pref
-  sShowTooltips =
-    nsContentUtils::GetBoolPref("browser.chrome.toolbar_tips", sShowTooltips);
-
-  // register the callback so we get notified of updates
-  nsContentUtils::RegisterPrefCallback("browser.chrome.toolbar_tips",
-                                       ToolbarTipsPrefChanged, this);
-
   return NS_OK;
 }
 

layout/xul/base/src/nsXULTooltipListener.h

@@ -105,6 +105,7 @@ protected:
   // pref callback for when the "show tooltips" pref changes
   static int sTooltipPrefChanged (const char* aPref, void* aData);
   static PRBool sShowTooltips;
+  static PRUint32 sTooltipListenerCount;
 
   void KillTooltipTimer();
   void CreateAutoHideTimer();