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 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 #include "nsCOMPtr.h"

 #include "nsString.h"

 #include "nsReadableUtils.h"

 #include "nsUnicharUtils.h"

 #include "nsTArray.h"

 #include "nsIBaseWindow.h"

 #include "nsIWidget.h"

 #include "nsIDOMWindow.h"

 #include "nsIObserverService.h"

 #include "nsIServiceManager.h"

 #include "nsISimpleEnumerator.h"

 #include "nsAppShellWindowEnumerator.h"

 #include "nsWindowMediator.h"

 #include "nsIWindowMediatorListener.h"

 #include "nsXPIDLString.h"

 #include "nsGlobalWindow.h"

 #include "nsIDocShell.h"

 #include "nsIInterfaceRequestor.h"

 #include "nsIInterfaceRequestorUtils.h"

 #include "nsIXULWindow.h"

 using namespace mozilla;

 static bool notifyOpenWindow(nsIWindowMediatorListener *aElement, void* aData);

 static bool notifyCloseWindow(nsIWindowMediatorListener *aElement, void* aData);

 static bool notifyWindowTitleChange(nsIWindowMediatorListener *aElement, void* aData);

 // for notifyWindowTitleChange

 struct WindowTitleData {

   nsIXULWindow* mWindow;

   const char16_t *mTitle;

 };

 nsresult

 nsWindowMediator::GetDOMWindow(nsIXULWindow* inWindow,

                                nsCOMPtr<nsIDOMWindow>& outDOMWindow)

 {

   nsCOMPtr<nsIDocShell> docShell;

   inWindow->GetDocShell(getter_AddRefs(docShell));

   outDOMWindow = do_GetInterface(docShell);

   return outDOMWindow ? NS_OK : NS_ERROR_FAILURE;

 }

 nsWindowMediator::nsWindowMediator() :

   mEnumeratorList(), mOldestWindow(nullptr), mTopmostWindow(nullptr),

   mTimeStamp(0), mSortingZOrder(false), mReady(false),

   mListLock("nsWindowMediator.mListLock")

 {

 }

 nsWindowMediator::~nsWindowMediator()

 {

   while (mOldestWindow)

     UnregisterWindow(mOldestWindow);

 }

 nsresult nsWindowMediator::Init()

 {

   nsresult rv;

   nsCOMPtr<nsIObserverService> obsSvc =

     do_GetService("@mozilla.org/observer-service;1", &rv);

   NS_ENSURE_SUCCESS(rv, rv);

   rv = obsSvc->AddObserver(this, "xpcom-shutdown", true);

   NS_ENSURE_SUCCESS(rv, rv);

   mReady = true;

   return NS_OK;

 }

 NS_IMETHODIMP nsWindowMediator::RegisterWindow(nsIXULWindow* inWindow)

 {

   NS_ENSURE_STATE(mReady);

   if (GetInfoFor(inWindow)) {

     NS_ERROR("multiple window registration");

     return NS_ERROR_FAILURE;

   }

   mTimeStamp++;

   // Create window info struct and add to list of windows

   nsWindowInfo* windowInfo = new nsWindowInfo(inWindow, mTimeStamp);

   if (!windowInfo)

     return NS_ERROR_OUT_OF_MEMORY;

   WindowTitleData winData = { inWindow, nullptr };

   mListeners.EnumerateForwards(notifyOpenWindow, &winData);

   MutexAutoLock lock(mListLock);

   if (mOldestWindow)

     windowInfo->InsertAfter(mOldestWindow->mOlder, nullptr);

   else

     mOldestWindow = windowInfo;

   return NS_OK;

 }

 NS_IMETHODIMP

 nsWindowMediator::UnregisterWindow(nsIXULWindow* inWindow)

 {

   NS_ENSURE_STATE(mReady);

   MutexAutoLock lock(mListLock);

   nsWindowInfo *info = GetInfoFor(inWindow);

   if (info)

     return UnregisterWindow(info);

   return NS_ERROR_INVALID_ARG;

 }

 nsresult

 nsWindowMediator::UnregisterWindow(nsWindowInfo *inInfo)

 {

   // Inform the iterators

   uint32_t index = 0;

   while (index < mEnumeratorList.Length()) {

     mEnumeratorList[index]->WindowRemoved(inInfo);

     index++;

   }

   WindowTitleData winData = { inInfo->mWindow.get(), nullptr };

   mListeners.EnumerateForwards(notifyCloseWindow, &winData);

   // Remove from the lists and free up 

   if (inInfo == mOldestWindow)

     mOldestWindow = inInfo->mYounger;

   if (inInfo == mTopmostWindow)

     mTopmostWindow = inInfo->mLower;

   inInfo->Unlink(true, true);

   if (inInfo == mOldestWindow)

     mOldestWindow = nullptr;

   if (inInfo == mTopmostWindow)

     mTopmostWindow = nullptr;

   delete inInfo;  

   return NS_OK;

 }

 nsWindowInfo*

 nsWindowMediator::GetInfoFor(nsIXULWindow *aWindow)

 {

   nsWindowInfo *info,

                *listEnd;

   if (!aWindow)

     return nullptr;

   info = mOldestWindow;

   listEnd = nullptr;

   while (info != listEnd) {

     if (info->mWindow.get() == aWindow)

       return info;

     info = info->mYounger;

     listEnd = mOldestWindow;

   }

   return nullptr;

 }

 nsWindowInfo*

 nsWindowMediator::GetInfoFor(nsIWidget *aWindow)

 {

   nsWindowInfo *info,

                *listEnd;

   if (!aWindow)

     return nullptr;

   info = mOldestWindow;

   listEnd = nullptr;

   nsCOMPtr<nsIWidget> scanWidget;

   while (info != listEnd) {

     nsCOMPtr<nsIBaseWindow> base(do_QueryInterface(info->mWindow));

     if (base)

       base->GetMainWidget(getter_AddRefs(scanWidget));

     if (aWindow == scanWidget.get())

       return info;

     info = info->mYounger;

     listEnd = mOldestWindow;

   }

   return nullptr;

 }

 NS_IMETHODIMP

 nsWindowMediator::GetEnumerator(const char16_t* inType, nsISimpleEnumerator** outEnumerator)

 {

   NS_ENSURE_ARG_POINTER(outEnumerator);

   NS_ENSURE_STATE(mReady);

   MutexAutoLock lock(mListLock);

   nsAppShellWindowEnumerator *enumerator = new nsASDOMWindowEarlyToLateEnumerator(inType, *this);

   if (enumerator)

     return enumerator->QueryInterface(NS_GET_IID(nsISimpleEnumerator) , (void**)outEnumerator);

   return NS_ERROR_OUT_OF_MEMORY;

 }

 NS_IMETHODIMP

 nsWindowMediator::GetXULWindowEnumerator(const char16_t* inType, nsISimpleEnumerator** outEnumerator)

 {

   NS_ENSURE_ARG_POINTER(outEnumerator);

   NS_ENSURE_STATE(mReady);

   MutexAutoLock lock(mListLock);

   nsAppShellWindowEnumerator *enumerator = new nsASXULWindowEarlyToLateEnumerator(inType, *this);

   if (enumerator)

     return enumerator->QueryInterface(NS_GET_IID(nsISimpleEnumerator) , (void**)outEnumerator);

   return NS_ERROR_OUT_OF_MEMORY;

 }

 NS_IMETHODIMP

 nsWindowMediator::GetZOrderDOMWindowEnumerator(

             const char16_t *aWindowType, bool aFrontToBack,

             nsISimpleEnumerator **_retval)

 {

   NS_ENSURE_ARG_POINTER(_retval);

   NS_ENSURE_STATE(mReady);

   MutexAutoLock lock(mListLock);

   nsAppShellWindowEnumerator *enumerator;

   if (aFrontToBack)

     enumerator = new nsASDOMWindowFrontToBackEnumerator(aWindowType, *this);

   else

     enumerator = new nsASDOMWindowBackToFrontEnumerator(aWindowType, *this);

   if (enumerator)

     return CallQueryInterface(enumerator, _retval);

   return NS_ERROR_OUT_OF_MEMORY;

 }

 NS_IMETHODIMP

 nsWindowMediator::GetZOrderXULWindowEnumerator(

             const char16_t *aWindowType, bool aFrontToBack,

             nsISimpleEnumerator **_retval)

 {

   NS_ENSURE_ARG_POINTER(_retval);

   NS_ENSURE_STATE(mReady);

   MutexAutoLock lock(mListLock);

   nsAppShellWindowEnumerator *enumerator;

   if (aFrontToBack)

     enumerator = new nsASXULWindowFrontToBackEnumerator(aWindowType, *this);

   else

     enumerator = new nsASXULWindowBackToFrontEnumerator(aWindowType, *this);

   if (enumerator)

     return CallQueryInterface(enumerator, _retval);

   return NS_ERROR_OUT_OF_MEMORY;

 }

 int32_t

 nsWindowMediator::AddEnumerator(nsAppShellWindowEnumerator * inEnumerator)

 {

   return mEnumeratorList.AppendElement(inEnumerator) != nullptr;

 }

 int32_t

 nsWindowMediator::RemoveEnumerator(nsAppShellWindowEnumerator * inEnumerator)

 {

   return mEnumeratorList.RemoveElement(inEnumerator);

 }

 // Returns the window of type inType ( if null return any window type ) which has the most recent

 // time stamp

 NS_IMETHODIMP

 nsWindowMediator::GetMostRecentWindow(const char16_t* inType, nsIDOMWindow** outWindow)

 {

   NS_ENSURE_ARG_POINTER(outWindow);

   *outWindow = nullptr;

   if (!mReady)

     return NS_OK;

   // Find the most window with the highest time stamp that matches

   // the requested type

   MutexAutoLock lock(mListLock);

   nsWindowInfo *info = MostRecentWindowInfo(inType);

   if (info && info->mWindow) {

     nsCOMPtr<nsIDOMWindow> DOMWindow;

     if (NS_SUCCEEDED(GetDOMWindow(info->mWindow, DOMWindow))) {  

       *outWindow = DOMWindow;

       NS_ADDREF(*outWindow);

       return NS_OK;

     }

     return NS_ERROR_FAILURE;

   }

   return NS_OK;

 }

 nsWindowInfo*

 nsWindowMediator::MostRecentWindowInfo(const char16_t* inType)

 {

   int32_t       lastTimeStamp = -1;

   nsAutoString  typeString(inType);

   bool          allWindows = !inType || typeString.IsEmpty();

   // Find the most window with the highest time stamp that matches

   // the requested type

   nsWindowInfo *searchInfo,

                *listEnd,

                *foundInfo = nullptr;

   searchInfo = mOldestWindow;

   listEnd = nullptr;

   while (searchInfo != listEnd) {

     if ((allWindows || searchInfo->TypeEquals(typeString)) &&

         searchInfo->mTimeStamp >= lastTimeStamp) {

       foundInfo = searchInfo;

       lastTimeStamp = searchInfo->mTimeStamp;

     }

     searchInfo = searchInfo->mYounger;

     listEnd = mOldestWindow;

   }

   return foundInfo;

 }

 NS_IMETHODIMP

 nsWindowMediator::GetOuterWindowWithId(uint64_t aWindowID,

                                        nsIDOMWindow** aWindow)

 {

   *aWindow = nsGlobalWindow::GetOuterWindowWithId(aWindowID);

   NS_IF_ADDREF(*aWindow);

   return NS_OK;

 }

 NS_IMETHODIMP

 nsWindowMediator::GetCurrentInnerWindowWithId(uint64_t aWindowID,

                                               nsIDOMWindow** aWindow)

 {

   nsCOMPtr<nsPIDOMWindow> inner = nsGlobalWindow::GetInnerWindowWithId(aWindowID);

   // not found

   if (!inner)

     return NS_OK;

   nsCOMPtr<nsPIDOMWindow> outer = inner->GetOuterWindow();

   NS_ENSURE_TRUE(outer, NS_ERROR_UNEXPECTED);

   // outer is already using another inner, so it's same as not found

   if (outer->GetCurrentInnerWindow() != inner)

     return NS_OK;

   nsCOMPtr<nsIDOMWindow> ret = do_QueryInterface(outer);

   ret.forget(aWindow);

   return NS_OK;

 }

 NS_IMETHODIMP

 nsWindowMediator::UpdateWindowTimeStamp(nsIXULWindow* inWindow)

 {

   NS_ENSURE_STATE(mReady);

   MutexAutoLock lock(mListLock);

   nsWindowInfo *info = GetInfoFor(inWindow);

   if (info) {

     // increment the window's time stamp

     info->mTimeStamp = ++mTimeStamp;

     return NS_OK;

   }

   return NS_ERROR_FAILURE; 

 }

 NS_IMETHODIMP

 nsWindowMediator::UpdateWindowTitle(nsIXULWindow* inWindow,

                                     const char16_t* inTitle)

 {

   NS_ENSURE_STATE(mReady);

   MutexAutoLock lock(mListLock);

   if (GetInfoFor(inWindow)) {

     WindowTitleData winData = { inWindow, inTitle };

     mListeners.EnumerateForwards(notifyWindowTitleChange, &winData);

   }

   return NS_OK;

 }

 /* This method's plan is to intervene only when absolutely necessary.

    We will get requests to place our windows behind unknown windows.

    For the most part, we need to leave those alone (turning them into

    explicit requests to be on top breaks Windows.) So generally we

    calculate a change as seldom as possible.

 */

 NS_IMETHODIMP

 nsWindowMediator::CalculateZPosition(

                 nsIXULWindow   *inWindow,

                 uint32_t        inPosition,

                 nsIWidget      *inBelow,

                 uint32_t       *outPosition,

                 nsIWidget     **outBelow,

                 bool           *outAltered)

 {

   NS_ENSURE_ARG_POINTER(outBelow);

   NS_ENSURE_STATE(mReady);

   *outBelow = nullptr;

   if (!inWindow || !outPosition || !outAltered)

     return NS_ERROR_NULL_POINTER;

   if (inPosition != nsIWindowMediator::zLevelTop &&

       inPosition != nsIWindowMediator::zLevelBottom &&

       inPosition != nsIWindowMediator::zLevelBelow)

     return NS_ERROR_INVALID_ARG;

   nsWindowInfo *info = mTopmostWindow;

   nsIXULWindow *belowWindow = nullptr;

   bool          found = false;

   nsresult      result = NS_OK;

   *outPosition = inPosition;

   *outAltered = false;

   if (mSortingZOrder) { // don't fight SortZOrder()

     *outBelow = inBelow;

     NS_IF_ADDREF(*outBelow);

     return NS_OK;

   }

   uint32_t inZ;

   GetZLevel(inWindow, &inZ);

   MutexAutoLock lock(mListLock);

   if (inPosition == nsIWindowMediator::zLevelBelow) {

     // locate inBelow. use topmost if it can't be found or isn't in the

     // z-order list

     info = GetInfoFor(inBelow);

     if (!info || (info->mYounger != info && info->mLower == info))

       info = mTopmostWindow;

     else

       found = true;

     if (!found) {

       /* Treat unknown windows as a request to be on top.

          Not as it should be, but that's what Windows gives us.

          Note we change inPosition, but not *outPosition. This forces

          us to go through the "on top" calculation just below, without

          necessarily changing the output parameters. */

       inPosition = nsIWindowMediator::zLevelTop;

     }

   }

   if (inPosition == nsIWindowMediator::zLevelTop) {

     if (mTopmostWindow && mTopmostWindow->mZLevel > inZ) {

       // asked for topmost, can't have it. locate highest allowed position.

       do {

         if (info->mZLevel <= inZ)

           break;

         info = info->mLower;

       } while (info != mTopmostWindow);

       *outPosition = nsIWindowMediator::zLevelBelow;

       belowWindow = info->mHigher->mWindow;

       *outAltered = true;

     }

   } else if (inPosition == nsIWindowMediator::zLevelBottom) {

     if (mTopmostWindow && mTopmostWindow->mHigher->mZLevel < inZ) {

       // asked for bottommost, can't have it. locate lowest allowed position.

       do {

         info = info->mHigher;

         if (info->mZLevel >= inZ)

           break;

       } while (info != mTopmostWindow);

       *outPosition = nsIWindowMediator::zLevelBelow;

       belowWindow = info->mWindow;

       *outAltered = true;

     }

   } else {

     unsigned long relativeZ;

     // check that we're in the right z-plane

     if (found) {

       belowWindow = info->mWindow;

       relativeZ = info->mZLevel;

       if (relativeZ > inZ) {

         // might be OK. is lower window, if any, lower?

         if (info->mLower != info && info->mLower->mZLevel > inZ) {

           do {

             if (info->mZLevel <= inZ)

               break;

             info = info->mLower;

           } while (info != mTopmostWindow);

           belowWindow = info->mHigher->mWindow;

           *outAltered = true;

         }

       } else if (relativeZ < inZ) {

         // nope. look for a higher window to be behind.

         do {

           info = info->mHigher;

           if (info->mZLevel >= inZ)

             break;

         } while (info != mTopmostWindow);

         if (info->mZLevel >= inZ)

           belowWindow = info->mWindow;

         else

           *outPosition = nsIWindowMediator::zLevelTop;

         *outAltered = true;

       } // else they're equal, so it's OK

     }

   }

   if (NS_SUCCEEDED(result) && belowWindow) {

     nsCOMPtr<nsIBaseWindow> base(do_QueryInterface(belowWindow));

     if (base)

       base->GetMainWidget(outBelow);

     else

       result = NS_ERROR_NO_INTERFACE;

   }

   return result;

 }

 NS_IMETHODIMP

 nsWindowMediator::SetZPosition(

                 nsIXULWindow *inWindow,

                 uint32_t      inPosition,

                 nsIXULWindow *inBelow)

 {

   nsWindowInfo *inInfo,

                *belowInfo;

   if ((inPosition != nsIWindowMediator::zLevelTop &&

        inPosition != nsIWindowMediator::zLevelBottom &&

        inPosition != nsIWindowMediator::zLevelBelow) ||

       !inWindow) {

     return NS_ERROR_INVALID_ARG;

   }

   if (mSortingZOrder) // don't fight SortZOrder()

     return NS_OK;

   NS_ENSURE_STATE(mReady);

   MutexAutoLock lock(mListLock);

   /* Locate inWindow and unlink it from the z-order list.

      It's important we look for it in the age list, not the z-order list.

      This is because the former is guaranteed complete, while

      now may be this window's first exposure to the latter. */

   inInfo = GetInfoFor(inWindow);

   if (!inInfo)

     return NS_ERROR_INVALID_ARG;

   // locate inBelow, place inWindow behind it

   if (inPosition == nsIWindowMediator::zLevelBelow) {

     belowInfo = GetInfoFor(inBelow);

     // it had better also be in the z-order list

     if (belowInfo &&

         belowInfo->mYounger != belowInfo && belowInfo->mLower == belowInfo) {

       belowInfo = nullptr;

     }

     if (!belowInfo) {

       if (inBelow)

         return NS_ERROR_INVALID_ARG;

       else

         inPosition = nsIWindowMediator::zLevelTop;

     }

   }

   if (inPosition == nsIWindowMediator::zLevelTop ||

       inPosition == nsIWindowMediator::zLevelBottom)

     belowInfo = mTopmostWindow ? mTopmostWindow->mHigher : nullptr;

   if (inInfo != belowInfo) {

     inInfo->Unlink(false, true);

     inInfo->InsertAfter(nullptr, belowInfo);

   }

   if (inPosition == nsIWindowMediator::zLevelTop)

     mTopmostWindow = inInfo;

   return NS_OK;

 }

 NS_IMETHODIMP

 nsWindowMediator::GetZLevel(nsIXULWindow *aWindow, uint32_t *_retval)

 {

   NS_ENSURE_ARG_POINTER(_retval);

   *_retval = nsIXULWindow::normalZ;

   nsWindowInfo *info = GetInfoFor(aWindow);

   if (info) {

     *_retval = info->mZLevel;

   } else {

     NS_WARNING("getting z level of unregistered window");

     // this goes off during window destruction

   }

   return NS_OK;

 }

 NS_IMETHODIMP

 nsWindowMediator::SetZLevel(nsIXULWindow *aWindow, uint32_t aZLevel)

 {

   NS_ENSURE_STATE(mReady);

   MutexAutoLock lock(mListLock);

   nsWindowInfo *info = GetInfoFor(aWindow);

   NS_ASSERTION(info, "setting z level of unregistered window");

   if (!info)

     return NS_ERROR_FAILURE;

   if (info->mZLevel != aZLevel) {

     bool lowered = info->mZLevel > aZLevel;

     info->mZLevel = aZLevel;

     if (lowered)

       SortZOrderFrontToBack();

     else

       SortZOrderBackToFront();

   }

   return NS_OK;

 }

 /*   Fix potentially out-of-order windows by performing an insertion sort

    on the z-order list. The method will work no matter how broken the

    list, but its assumed usage is immediately after one window's z level

    has been changed, so one window is potentially out of place. Such a sort

    is most efficiently done in a particular direction. Use this one

    if a window's z level has just been reduced, so the sort is most efficiently

    done front to back. Assumes caller has locked mListLock.

      Note it's hardly worth going to all the trouble to write two versions

    of this method except that if we choose the inefficient sorting direction,

    on slow systems windows could visibly bubble around the window that

    was moved.

 */

 void

 nsWindowMediator::SortZOrderFrontToBack()

 {

   nsWindowInfo *scan,   // scans list looking for problems

                *search, // searches for correct placement for scan window

                *prev,   // previous search element

                *lowest; // bottom-most window in list

   bool         finished;

   if (!mTopmostWindow) // early during program execution there's no z list yet

     return;            // there's also only one window, so this is not dangerous

   mSortingZOrder = true;

   /* Step through the list from top to bottom. If we find a window which

      should be moved down in the list, move it to its highest legal position. */

   do {

     finished = true;

     lowest = mTopmostWindow->mHigher;

     scan = mTopmostWindow;

     while (scan != lowest) {

       uint32_t scanZ = scan->mZLevel;

       if (scanZ < scan->mLower->mZLevel) { // out of order

         search = scan->mLower;

         do {

           prev = search;

           search = search->mLower;

         } while (prev != lowest && scanZ < search->mZLevel);

         // reposition |scan| within the list

         if (scan == mTopmostWindow)

           mTopmostWindow = scan->mLower;

         scan->Unlink(false, true);

         scan->InsertAfter(nullptr, prev);

         // fix actual window order

         nsCOMPtr<nsIBaseWindow> base;

         nsCOMPtr<nsIWidget> scanWidget;

         nsCOMPtr<nsIWidget> prevWidget;

         base = do_QueryInterface(scan->mWindow);

         if (base)

           base->GetMainWidget(getter_AddRefs(scanWidget));

         base = do_QueryInterface(prev->mWindow);

         if (base)

           base->GetMainWidget(getter_AddRefs(prevWidget));

         if (scanWidget)

           scanWidget->PlaceBehind(eZPlacementBelow, prevWidget, false);

         finished = false;

         break;

       }

       scan = scan->mLower;

     }

   } while (!finished);

   mSortingZOrder = false;

 }

 // see comment for SortZOrderFrontToBack

 void

 nsWindowMediator::SortZOrderBackToFront()

 {

   nsWindowInfo *scan,   // scans list looking for problems

                *search, // searches for correct placement for scan window

                *lowest; // bottom-most window in list

   bool         finished;

   if (!mTopmostWindow) // early during program execution there's no z list yet

     return;            // there's also only one window, so this is not dangerous

   mSortingZOrder = true;

   /* Step through the list from bottom to top. If we find a window which

      should be moved up in the list, move it to its lowest legal position. */

   do {

     finished = true;

     lowest = mTopmostWindow->mHigher;

     scan = lowest;

     while (scan != mTopmostWindow) {

       uint32_t scanZ = scan->mZLevel;

       if (scanZ > scan->mHigher->mZLevel) { // out of order

         search = scan;

         do {

           search = search->mHigher;

         } while (search != lowest && scanZ > search->mZLevel);

         // reposition |scan| within the list

         if (scan != search && scan != search->mLower) {

           scan->Unlink(false, true);

           scan->InsertAfter(nullptr, search);

         }

         if (search == lowest)

           mTopmostWindow = scan;

         // fix actual window order

         nsCOMPtr<nsIBaseWindow> base;

         nsCOMPtr<nsIWidget> scanWidget;

         nsCOMPtr<nsIWidget> searchWidget;

         base = do_QueryInterface(scan->mWindow);

         if (base)

           base->GetMainWidget(getter_AddRefs(scanWidget));

         if (mTopmostWindow != scan) {

           base = do_QueryInterface(search->mWindow);

           if (base)

             base->GetMainWidget(getter_AddRefs(searchWidget));

         }

         if (scanWidget)

           scanWidget->PlaceBehind(eZPlacementBelow, searchWidget, false);

         finished = false;

         break;

       }

       scan = scan->mHigher;

     }

   } while (!finished);

   mSortingZOrder = false;

 }

 NS_IMPL_ISUPPORTS(nsWindowMediator,

   nsIWindowMediator,

   nsIObserver,

   nsISupportsWeakReference)

 NS_IMETHODIMP

 nsWindowMediator::AddListener(nsIWindowMediatorListener* aListener)

 {

   NS_ENSURE_ARG_POINTER(aListener);

   mListeners.AppendObject(aListener);

   return NS_OK;

 }

 NS_IMETHODIMP

 nsWindowMediator::RemoveListener(nsIWindowMediatorListener* aListener)

 {

   NS_ENSURE_ARG_POINTER(aListener);

   mListeners.RemoveObject(aListener);

   return NS_OK;

 }

 NS_IMETHODIMP

 nsWindowMediator::Observe(nsISupports* aSubject,

                           const char* aTopic,

                           const char16_t* aData)

 {

   if (!strcmp(aTopic, "xpcom-shutdown") && mReady) {

     // Unregistering a window may cause its destructor to run, causing it to

     // call into the window mediator, try to acquire mListLock, and deadlock.

     // Our solution is to hold strong refs to all windows until we release

     // mListLock.

     nsTArray<nsCOMPtr<nsIXULWindow> > windows;

     {

       MutexAutoLock lock(mListLock);

       while (mOldestWindow) {

         windows.AppendElement(mOldestWindow->mWindow);

         UnregisterWindow(mOldestWindow);

       }

     }

     mReady = false;

   }

   return NS_OK;

 }

 bool

 notifyOpenWindow(nsIWindowMediatorListener *aListener, void* aData)

 {

   WindowTitleData* winData = static_cast<WindowTitleData*>(aData);

   aListener->OnOpenWindow(winData->mWindow);

   return true;

 }

 bool

 notifyCloseWindow(nsIWindowMediatorListener *aListener, void* aData)

 {

   WindowTitleData* winData = static_cast<WindowTitleData*>(aData);

   aListener->OnCloseWindow(winData->mWindow);

   return true;

 }

 bool 

 notifyWindowTitleChange(nsIWindowMediatorListener *aListener, void* aData)

 {

   WindowTitleData* titleData = reinterpret_cast<WindowTitleData*>(aData);

   aListener->OnWindowTitleChange(titleData->mWindow, titleData->mTitle);

   return true;

 }