Issue #1467, #3397 - Rewrite the map from threads to tabs

src/plugin/PluginClass.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
- * Copyright (C) 2006-2015 Eyeo GmbH
+ * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
@@ skipping 43 matching lines @@
 
 ATOM CPluginClass::s_atomPaneClass = NULL;
 HINSTANCE CPluginClass::s_hUxtheme = NULL;
 std::set<CPluginClass*> CPluginClass::s_instances;
 
 CComAutoCriticalSection CPluginClass::s_criticalSectionLocal;
 CComAutoCriticalSection CPluginClass::s_criticalSectionWindow;
 
 CComQIPtr<IWebBrowser2> CPluginClass::s_asyncWebBrowser2;
 
-

[sergei, 2016/02/01 15:50:43]

Why not to put it into anonymous namespace?

[Eric, 2016/02/03 17:17:05]

OK.

-/**
- * A synchronized map whose key is always the current thread ID.
- */
-class CurrentThreadMap
-  : public SyncMap<DWORD, CPluginClass*, nullptr>
-{
-  typedef SyncMap<DWORD, CPluginClass*, nullptr> Base;
-
-public:
-  bool AddIfAbsent(CPluginClass* p)
-  {
-    return Base::AddIfAbsent(::GetCurrentThreadId(), p);
-  }
-
-  bool RemoveAndCheck()
-  {
-    return Base::RemoveAndCheck(::GetCurrentThreadId());
-  }
-
-  CPluginClass* Locate()
-  {
-    return Base::Locate(::GetCurrentThreadId());
-  }
-};
-
-/**
- * Map from thread ID's to CPluginClass instances
- */
-CurrentThreadMap threadMap;

[sergei, 2016/02/01 15:50:43]

Off topic: Still a global variable. When will we stop it?...

[Eric, 2016/02/03 17:17:05]

The map from threads to BHO instances is inherently a singleton, and thus will
always act much like a global. Just can't get around it.

Global variables are not inherently bad. Global variables that could be scoped
smaller are what's bad. With the state that 'CPluginClass' is in right now,
combining BHO and UI responsibilities, we can't do incrementally better.

+namespace
+{
+  /**
+   * A synchronized map whose key is always the current thread ID.
+   */
+  class CurrentThreadMap
+    : public SyncMap<DWORD, CPluginClass*, nullptr>
+  {
+    typedef SyncMap<DWORD, CPluginClass*, nullptr> Base;
+
+  public:
+    bool AddIfAbsent(CPluginClass* p)
+    {
+      return Base::AddIfAbsent(::GetCurrentThreadId(), p);
+    }
+
+    bool RemoveAndCheck()
+    {
+      return Base::RemoveIfPresent(::GetCurrentThreadId());
+    }
+
+    CPluginClass* Locate()
+    {
+      return Base::Locate(::GetCurrentThreadId());
+    }
+  };
+
+  /**
+   * Map from thread ID's to CPluginClass instances
+   */
+  CurrentThreadMap threadMap;
+}
 
 /*
  * Without namespace declaration, the identifier "Rectangle" is ambiguous
  * See http://msdn.microsoft.com/en-us/library/windows/desktop/dd162898(v=vs.85).aspx
  */
 namespace AdblockPlus
 {
   /**
     * Replacement for ATL type CRect.
     */
   class Rectangle
     : public RECT
   {
   public:
-    int Height() const
-    {
-      return bottom - top;
-    }
-
-    int Width() const
-    {
-      return right - left;
+    unsigned long Height() const
+    {
+      if (bottom < top)
+      {
+        throw std::runtime_error("invariant violation: rectangle bottom < top");
+      }
+      return static_cast<unsigned long>(bottom - top);
+    }
+
+    unsigned long Width() const
+    {
+      if (right < left)
+      {
+        throw std::runtime_error("invariant violation: rectangle right < left");
+      }
+      return static_cast<unsigned long>(right - left);
     }
   };
 }
 
 CPluginClass::CPluginClass()
   : m_webBrowser2(nullptr)
 {
+  DEBUG_GENERAL([this]() -> std::wstring
+    {
+      std::wstring s = L"CPluginClass::<constructor>, this = ";
+      s += ToHexLiteral(this);
+      return s;
+    }());
+
   //Use this line to debug memory leaks
   //    _CrtDumpMemoryLeaks();
 
   m_isAdvised = false;
   m_hTabWnd = NULL;
   m_hStatusBarWnd = NULL;
   m_hPaneWnd = NULL;
   m_nPaneWidth = 0;
   m_pWndProcStatus = NULL;
   m_hTheme = NULL;
   m_isInitializedOk = false;
-  m_tab = new CPluginTab(this);
+  m_tab = new CPluginTab();
   Dictionary::Create(GetBrowserLanguage());
 }
 
 CPluginClass::~CPluginClass()
 {
+  DEBUG_GENERAL([this]() -> std::wstring
+    {
+      std::wstring s = L"CPluginClass::<destructor>, this = ";
+      s += ToHexLiteral(this);
+      return s;
+    }());
+
   delete m_tab;
 }
 
 HWND CPluginClass::GetBrowserHWND() const
 {
   if (!m_webBrowser2)
   {
     DEBUG_ERROR_LOG(0, 0, 0, "CPluginClass::GetBrowserHWND - Reached with m_webBrowser2 == nullptr");
     return nullptr;
   }
@@ skipping 24 matching lines @@
 
   return browser;
 }
 
 std::wstring CPluginClass::GetBrowserUrl() const
 {
   std::wstring url;
   if (m_webBrowser2)
   {
     CComBSTR bstrURL;
-    if (SUCCEEDED(m_webBrowser2->get_LocationURL(&bstrURL)) && bstrURL)
-    {
-      url = std::wstring(bstrURL, SysStringLen(bstrURL));
+    if (SUCCEEDED(m_webBrowser2->get_LocationURL(&bstrURL)))
+    {
+      url = ToWstring(bstrURL);
     }
   }
   else
   {
-    DEBUG_ERROR_LOG(0, 0, 0, "CPluginClass::GetBrowserUrl - Reached with m_webBrowser2 == nullptr");
+    DEBUG_GENERAL(L"CPluginClass::GetBrowserUrl - Reached with m_webBrowser2 == nullptr (probable invariant violation)");
+  }
+  if (url.empty())
+  {
     url = m_tab->GetDocumentUrl();
   }
   return url;
 }
 
 DWORD WINAPI CPluginClass::StartInitObject(LPVOID thisPtr)
 {
   if (thisPtr == NULL)
     return 0;
   if (!((CPluginClass*)thisPtr)->InitObject())
@@ skipping 13 matching lines @@
  * 'unknownSite' will be null. Extraordinarily, this is sometimes _not_ called when IE
  * is shutting down. Thus 'SetSite(nullptr)' has some similarities with a destructor,
  * but it is not a proper substitute for one.
  */
 STDMETHODIMP CPluginClass::SetSite(IUnknown* unknownSite)
 {
   try
   {
     if (unknownSite)
     {
-
-      DEBUG_GENERAL(L"================================================================================\nNEW TAB UI\n================================================================================")
+      DEBUG_GENERAL(L"================================================================================\nNEW TAB UI\n================================================================================");
 
       HRESULT hr = ::CoInitialize(NULL);
       if (FAILED(hr))
       {
         DEBUG_ERROR_LOG(hr, PLUGIN_ERROR_SET_SITE, PLUGIN_ERROR_SET_SITE_COINIT, "Class::SetSite - CoInitialize");
       }
 
       /*
        * We were instantiated as a BHO, so our site is always of type IWebBrowser2.
        */
       m_webBrowser2 = ATL::CComQIPtr<IWebBrowser2>(unknownSite);
       if (!m_webBrowser2)
       {
         throw std::logic_error("CPluginClass::SetSite - Unable to convert site pointer to IWebBrowser2*");
       }
+      DEBUG_GENERAL([this]() -> std::wstring
+        {
+          std::wstringstream ss;
+          ss << L"CPluginClass::SetSite, this = " << ToHexLiteral(this);
+          ss << L", browser = " << ToHexLiteral(m_webBrowser2);
+          return ss.str();
+        }());
 
       /*
        * Add ourselves to the thread map.
        */
       if (!threadMap.AddIfAbsent(this))
       {
         throw std::logic_error("CPluginClass::SetSite - May not overwrite existing entry in thread map");

[sergei, 2016/02/01 15:50:43]

That looks suspicious. It can happen that two instances are instantiated in one
thread and it should be fine for us.
By throwing the exception here, we are basically breaking the functionality for
any other instance created using the same thread.

[Eric, 2016/02/03 17:17:05]

Actually, that cannot happen. 

       }
 
       //register the mimefilter
       //and only mimefilter
       //on some few computers the mimefilter does not get properly registered when it is done on another thread
       s_criticalSectionLocal.Lock();
       {
         // Always register on startup, then check if we need to unregister in a separate thread
         s_mimeFilter = CPluginClientFactory::GetMimeFilterClientInstance();
         s_asyncWebBrowser2 = unknownSite;
         s_instances.insert(this);
       }
       s_criticalSectionLocal.Unlock();
 
       try
       {
-        DEBUG_GENERAL("Loaded as BHO");
         HRESULT hr = DispEventAdvise(m_webBrowser2);
         if (SUCCEEDED(hr))
         {
           m_isAdvised = true;
           try
           {
             std::thread startInitObjectThread(StartInitObject, this);
             startInitObjectThread.detach(); // TODO: but actually we should wait for the thread in the dtr.
           }
           catch (const std::system_error& ex)
           {
             DEBUG_SYSTEM_EXCEPTION(ex, PLUGIN_ERROR_THREAD, PLUGIN_ERROR_MAIN_THREAD_CREATE_PROCESS, 
               "Class::Thread - Failed to create StartInitObject thread");
           }
         }
         else
         {
           DEBUG_ERROR_LOG(hr, PLUGIN_ERROR_SET_SITE, PLUGIN_ERROR_SET_SITE_ADVICE, "Class::SetSite - Advise");
         }
       }
       catch (const std::runtime_error& ex)
       {
         DEBUG_EXCEPTION(ex);
         Unadvise();
       }
     }
     else
     {
+      DEBUG_GENERAL([this]() -> std::wstring
+      {
+        std::wstringstream ss;
+        ss << L"CPluginClass::SetSite, this = " << ToHexLiteral(this);
+        ss << L", browser = nullptr";
+        return ss.str();
+      }());
+
       Unadvise();
 
       // Destroy window
       if (m_pWndProcStatus)
       {
         ::SetWindowLongPtr(m_hStatusBarWnd, GWLP_WNDPROC, (LPARAM)(WNDPROC)m_pWndProcStatus);
 
         m_pWndProcStatus = NULL;
       }
 
@@ skipping 168 matching lines @@
   {
     ATL::CComQIPtr<IWebBrowser2> webBrowser = frameBrowserDisp;
     if (!webBrowser)
     {
       return;
     }
     if (!urlVariant || urlVariant->vt != VT_BSTR)
     {
       return;
     }
-    std::wstring url(urlVariant->bstrVal, SysStringLen(urlVariant->bstrVal));
+    std::wstring url = ToWstring(urlVariant->bstrVal);
 
     // If webbrowser2 is equal to top level browser (as set in SetSite), we are
     // navigating new page
     CPluginClient* client = CPluginClient::GetInstance();
     if (url.find(L"javascript") == 0)
     {
     }
     else if (IsRootBrowser(webBrowser))
     {
       m_tab->OnNavigate(url);
@@ skipping 481 matching lines @@
   s_criticalSectionLocal.Unlock();
 
   return result;
 }
 
 CPluginTab* CPluginClass::GetTab()
 {
   return m_tab;
 }
 
-CPluginTab* CPluginClass::GetTabCurrentThread()
+CPluginTab* CPluginClass::GetTabForCurrentThread()
 {
   auto p = threadMap.Locate();
   return p ? p->m_tab : nullptr;
 }
 
-
+// Entry point
 STDMETHODIMP CPluginClass::QueryStatus(const GUID* pguidCmdGroup, ULONG cCmds, OLECMD prgCmds[], OLECMDTEXT* pCmdText)
 {
-  if (cCmds == 0) return E_INVALIDARG;
-  if (prgCmds == 0) return E_POINTER;
-
-  prgCmds[0].cmdf = OLECMDF_ENABLED;
-
+  try
+  {
+    if (cCmds == 0) return E_INVALIDARG;
+    if (prgCmds == 0) return E_POINTER;
+
+    prgCmds[0].cmdf = OLECMDF_ENABLED;
+  }
+  catch (...)
+  {
+    DEBUG_GENERAL(L"CPluginClass::QueryStatus - exception");
+    return E_FAIL;
+  }
   return S_OK;
 }
 
 HMENU CPluginClass::CreatePluginMenu(const std::wstring& url)
 {
   DEBUG_GENERAL("CreatePluginMenu");
   HINSTANCE hInstance = _AtlBaseModule.GetModuleInstance();
 
   HMENU hMenu = ::LoadMenu(hInstance, MAKEINTRESOURCE(IDR_MENU1));
 
@@ skipping 129 matching lines @@
 
   MENUITEMINFOW miiSep = {};
   miiSep.cbSize = sizeof(miiSep);
   miiSep.fMask = MIIM_TYPE | MIIM_FTYPE;
   miiSep.fType = MFT_SEPARATOR;
 
   CPluginClient* client = CPluginClient::GetInstance();
   CPluginSettings* settings = CPluginSettings::GetInstance();
   {
     ctext = dictionary->Lookup("menu", "menu-disable-on-site");
-    // Is domain in white list?
     ReplaceString(ctext, L"?1?", client->GetHostFromUrl(url));
-    if (client->IsWhitelistedUrl(GetTab()->GetDocumentUrl()))
-    {
+    /*
+     * The display state of the "disable on this site" menu item depends upon tab content
+     */
+    if (!GetTab()->IsPossibleToDisableOnSite())
+    {
+      // Since we can't disable the present content,
+      // it makes no sense to offer the user an option to block it.
+      fmii.fState = MFS_UNCHECKED | MFS_DISABLED;
+    }
+    else if (client->IsWhitelistedUrl(GetTab()->GetDocumentUrl()))
+    {
+      // Domain is in white list, indicated by a check mark
       fmii.fState = MFS_CHECKED | MFS_ENABLED;
     }
     else
     {
       fmii.fState = MFS_UNCHECKED | MFS_ENABLED;
     }
     fmii.fMask = MIIM_STRING | MIIM_STATE;
     fmii.dwTypeData = const_cast<LPWSTR>(ctext.c_str());
     fmii.cch = static_cast<UINT>(ctext.size());
 
@@ skipping 28 matching lines @@
   ctext = dictionary->Lookup("menu", "menu-settings");
   fmii.fMask  = MIIM_STATE | MIIM_STRING;
   fmii.fState = MFS_ENABLED;
   fmii.dwTypeData = const_cast<LPWSTR>(ctext.c_str());
   fmii.cch = static_cast<UINT>(ctext.size());
   ::SetMenuItemInfoW(hMenu, ID_MENU_SETTINGS, FALSE, &fmii);
 
   return true;
 }
 
-
+// Entry point
 STDMETHODIMP CPluginClass::Exec(const GUID*, DWORD nCmdID, DWORD, VARIANTARG*, VARIANTARG*)
 {
-  HWND hBrowserWnd = GetBrowserHWND();
-  if (!hBrowserWnd)
-  {
-    return E_FAIL;
-  }
-
-  // Create menu
-  HMENU hMenu = CreatePluginMenu(m_tab->GetDocumentUrl());
-  if (!hMenu)
-  {
-    return E_FAIL;
-  }
-
-  // Check if button in toolbar was pressed
-  int nIDCommand = -1;
-  BOOL bRightAlign = FALSE;
-
-  POINT pt;
-  GetCursorPos(&pt);
-
-  HWND hWndToolBar = ::WindowFromPoint(pt);
-
-  DWORD nProcessId;
-  ::GetWindowThreadProcessId(hWndToolBar, &nProcessId);
-
-  if (hWndToolBar && ::GetCurrentProcessId() == nProcessId)
-  {
-    ::ScreenToClient(hWndToolBar, &pt);
-    int nButton = (int)::SendMessage(hWndToolBar, TB_HITTEST, 0, (LPARAM)&pt);
-
-    if (nButton > 0)
-    {
-      TBBUTTON pTBBtn = {};
-
-      if (SendMessage(hWndToolBar, TB_GETBUTTON, nButton, (LPARAM)&pTBBtn))
-      {
-        RECT rcButton;
-        nIDCommand = pTBBtn.idCommand;
-
-        if (SendMessage(hWndToolBar, TB_GETRECT, nIDCommand, (LPARAM)&rcButton))
-        {
-          pt.x = rcButton.left;
-          pt.y = rcButton.bottom;
-          ClientToScreen(hWndToolBar, &pt);
-
-          RECT rcWorkArea;
-          SystemParametersInfo(SPI_GETWORKAREA, 0, (LPVOID)&rcWorkArea, 0);
-          if (rcWorkArea.right - pt.x < 150)
+  try
+  {
+    HWND hBrowserWnd = GetBrowserHWND();
+    if (!hBrowserWnd)
+    {
+      return E_FAIL;
+    }
+
+    // Create menu
+    HMENU hMenu = CreatePluginMenu(m_tab->GetDocumentUrl());
+    if (!hMenu)
+    {
+      return E_FAIL;
+    }
+
+    // Check if button in toolbar was pressed
+    int nIDCommand = -1;
+    BOOL bRightAlign = FALSE;
+
+    POINT pt;
+    GetCursorPos(&pt);
+
+    HWND hWndToolBar = ::WindowFromPoint(pt);
+
+    DWORD nProcessId;
+    ::GetWindowThreadProcessId(hWndToolBar, &nProcessId);
+
+    if (hWndToolBar && ::GetCurrentProcessId() == nProcessId)
+    {
+      ::ScreenToClient(hWndToolBar, &pt);
+      int nButton = (int)::SendMessage(hWndToolBar, TB_HITTEST, 0, (LPARAM)&pt);
+
+      if (nButton > 0)
+      {
+        TBBUTTON pTBBtn = {};
+
+        if (SendMessage(hWndToolBar, TB_GETBUTTON, nButton, (LPARAM)&pTBBtn))
+        {
+          RECT rcButton;
+          nIDCommand = pTBBtn.idCommand;
+
+          if (SendMessage(hWndToolBar, TB_GETRECT, nIDCommand, (LPARAM)&rcButton))
           {
-            bRightAlign = TRUE;
-            pt.x = rcButton.right;
+            pt.x = rcButton.left;
             pt.y = rcButton.bottom;
             ClientToScreen(hWndToolBar, &pt);
+
+            RECT rcWorkArea;
+            SystemParametersInfo(SPI_GETWORKAREA, 0, (LPVOID)&rcWorkArea, 0);
+            if (rcWorkArea.right - pt.x < 150)
+            {
+              bRightAlign = TRUE;
+              pt.x = rcButton.right;
+              pt.y = rcButton.bottom;
+              ClientToScreen(hWndToolBar, &pt);
+            }
           }
         }
       }
+      else
+      {
+        GetCursorPos(&pt);
+      }
+    }
+
+    // Display menu
+    UINT nFlags = 0;
+    if (bRightAlign)
+    {
+      nFlags |= TPM_RIGHTALIGN;
     }
     else
     {
-      GetCursorPos(&pt);
-    }
-  }
-
-  // Display menu
-  UINT nFlags = 0;
-  if (bRightAlign)
-  {
-    nFlags |= TPM_RIGHTALIGN;
-  }
-  else
-  {
-    nFlags |= TPM_LEFTALIGN;
-  }
-
-  DisplayPluginMenu(hMenu, nIDCommand, pt, nFlags);
+      nFlags |= TPM_LEFTALIGN;
+    }
+
+    DisplayPluginMenu(hMenu, nIDCommand, pt, nFlags);
+  }
+  catch (...)
+  {
+    // Suppress exception, log only
+    DEBUG_GENERAL(L"CPluginClass::Exec - exception");
+    return E_FAIL;
+  }
 
   return S_OK;
 }
 
-/////////////////////////////////////////////////////////////////////////////
-// Window procedures
-
+// Entry point
 LRESULT CALLBACK CPluginClass::NewStatusProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 {
-  // Find tab
-  CPluginClass *pClass = FindInstance(hWnd);
-  if (!pClass)
-  {
-    return DefWindowProc(hWnd, message, wParam, lParam);
-  }
-
-  // Process message
-  switch (message)
-  {
-  case SB_SIMPLE:
-    {
-      ShowWindow(pClass->m_hPaneWnd, !wParam);
+  CPluginClass *pClass;
+  try
+  {
+    // Find tab
+    pClass = FindInstance(hWnd);
+    if (!pClass)
+    {
+      /*
+       * Race condition if reached.
+       * We did not unhook the window procedure for the status bar when the last BHO instance using it terminated.
+       * The next best thing is to call the system default window function.
+       */
+      return DefWindowProc(hWnd, message, wParam, lParam);
+    }
+
+    // Process message
+    switch (message)
+    {
+    case SB_SIMPLE:
+      {
+        ShowWindow(pClass->m_hPaneWnd, !wParam);
+        break;
+      }
+
+    case WM_SYSCOLORCHANGE:
+      {
+        pClass->UpdateTheme();
+        break;
+      }
+
+    case SB_SETPARTS:
+      {
+        if (!lParam || !wParam || wParam > 30 || !IsWindow(pClass->m_hPaneWnd))
+        {
+          return CallWindowProc(pClass->m_pWndProcStatus, hWnd, message, wParam, lParam);
+        }
+
+        WPARAM nParts = wParam;
+        if (STATUSBAR_PANE_NUMBER >= nParts)
+        {
+          return CallWindowProc(pClass->m_pWndProcStatus, hWnd, message, wParam, lParam);
+        }
+
+        HLOCAL hLocal = LocalAlloc(LHND, sizeof(int) * (nParts + 1));
+        LPINT lpParts = (LPINT)LocalLock(hLocal);
+        memcpy(lpParts, (void*)lParam, wParam*sizeof(int));
+
+        for (unsigned i = 0; i < STATUSBAR_PANE_NUMBER; i++)
+        {
+          lpParts[i] -= pClass->m_nPaneWidth;
+        }
+        LRESULT hRet = CallWindowProc(pClass->m_pWndProcStatus, hWnd, message, wParam, (LPARAM)lpParts);
+
+        AdblockPlus::Rectangle rcPane;
+        ::SendMessage(hWnd, SB_GETRECT, STATUSBAR_PANE_NUMBER, (LPARAM)&rcPane);
+
+        AdblockPlus::Rectangle rcClient;
+        ::GetClientRect(hWnd, &rcClient);
+
+        ::MoveWindow(
+          pClass->m_hPaneWnd,
+          lpParts[STATUSBAR_PANE_NUMBER] - pClass->m_nPaneWidth,
+          0,
+          pClass->m_nPaneWidth,
+          rcClient.Height(),
+          TRUE);
+
+        ::LocalFree(hLocal);
+        return hRet;
+      }
+
+    default:
       break;
     }
-
-  case WM_SYSCOLORCHANGE:
-    {
-      pClass->UpdateTheme();
-      break;
-    }
-
-  case SB_SETPARTS:
-    {
-      if (!lParam || !wParam || wParam > 30 || !IsWindow(pClass->m_hPaneWnd))
-      {
-        return CallWindowProc(pClass->m_pWndProcStatus, hWnd, message, wParam, lParam);
-      }
-
-      WPARAM nParts = wParam;
-      if (STATUSBAR_PANE_NUMBER >= nParts)
-      {
-        return CallWindowProc(pClass->m_pWndProcStatus, hWnd, message, wParam, lParam);
-      }
-
-      HLOCAL hLocal = LocalAlloc(LHND, sizeof(int) * (nParts+1));
-      LPINT lpParts = (LPINT)LocalLock(hLocal);
-      memcpy(lpParts, (void*)lParam, wParam*sizeof(int));
-
-      for (unsigned i = 0; i < STATUSBAR_PANE_NUMBER; i++)
-      {
-        lpParts[i] -= pClass->m_nPaneWidth;
-      }
-      LRESULT hRet = CallWindowProc(pClass->m_pWndProcStatus, hWnd, message, wParam, (LPARAM)lpParts);
-
-      AdblockPlus::Rectangle rcPane;
-      ::SendMessage(hWnd, SB_GETRECT, STATUSBAR_PANE_NUMBER, (LPARAM)&rcPane);
-
-      AdblockPlus::Rectangle rcClient;
-      ::GetClientRect(hWnd, &rcClient);
-
-      ::MoveWindow(
-        pClass->m_hPaneWnd,
-        lpParts[STATUSBAR_PANE_NUMBER] - pClass->m_nPaneWidth,
-        0,
-        pClass->m_nPaneWidth,
-        rcClient.Height(),
-        TRUE);
-
-      ::LocalFree(hLocal);
-
-
-      return hRet;
-    }
-
-  default:
-    break;
-  }
-
-  LRESULT result = CallWindowProc(pClass->m_pWndProcStatus, hWnd, message, wParam, lParam);
-
-
-  return result;
-
+  }
+  catch (...)
+  {
+    // Suppress exception. Fall through to default handler.
+    DEBUG_GENERAL(L"CPluginClass::NewStatusProc - exception");
+  }
+  return ::CallWindowProc(pClass->m_pWndProcStatus, hWnd, message, wParam, lParam);
 }
 
 
 HICON CPluginClass::GetStatusBarIcon(const std::wstring& url)
 {
   // use the disable icon as defualt, if the client doesn't exists
   HICON hIcon = GetIcon(ICON_PLUGIN_DEACTIVATED);
 
-  CPluginTab* tab = GetTabCurrentThread();
+  CPluginTab* tab = GetTabForCurrentThread();
   if (tab)
   {
     CPluginClient* client = CPluginClient::GetInstance();
     if (CPluginSettings::GetInstance()->IsPluginEnabled())
     {
       if (client->IsWhitelistedUrl(url))
       {
         hIcon = GetIcon(ICON_PLUGIN_DISABLED);
       }
       else
       {
         CPluginSettings* settings = CPluginSettings::GetInstance();
         hIcon = GetIcon(ICON_PLUGIN_ENABLED);
       }
     }
   }
   return hIcon;
 }
 
-
+// Entry point
 LRESULT CALLBACK CPluginClass::PaneWindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 {
-  // Find tab
-  CPluginClass *pClass = FindInstance(GetParent(hWnd));
-  if (!pClass)
-  {
-    return ::DefWindowProc(hWnd, message, wParam, lParam);
-  }
-
-  // Process message
-  switch (message)
-  {
-
-  case WM_SETCURSOR:
-    {
-      ::SetCursor(::LoadCursor(NULL, IDC_ARROW));
-      return TRUE;
-    }
-  case WM_PAINT:
-    {
-      PAINTSTRUCT ps;
-      HDC hDC = ::BeginPaint(hWnd, &ps);
-
-      AdblockPlus::Rectangle rcClient;
-      ::GetClientRect(hWnd, &rcClient);
-
-      int nDrawEdge = 0;
-
-      // Old Windows background drawing
-      if (pClass->m_hTheme == NULL)
-      {
-        ::FillRect(hDC, &rcClient, (HBRUSH)(COLOR_BTNFACE + 1));
-        ::DrawEdge(hDC, &rcClient, BDR_RAISEDINNER, BF_LEFT);
-
-        nDrawEdge = 3;
-        rcClient.left += 3;
-
-        ::DrawEdge(hDC, &rcClient, BDR_SUNKENOUTER, BF_RECT);
-      }
-      // Themed background drawing
-      else
-      {
-        // Draw background
-        if (pfnDrawThemeBackground)
-        {
-          AdblockPlus::Rectangle rc = rcClient;
-          rc.right -= 2;
-          pfnDrawThemeBackground(pClass->m_hTheme, hDC, 0, 0, &rc, NULL);
-        }
-
-        // Copy separator picture to left side
-        int nHeight = rcClient.Height();
-        int nWidth = rcClient.Width() - 2;
-
-        for (int i = 0; i < 2; i++)
-        {
-          for (int j = 0; j < nHeight; j++)
+  try
+  {
+    // Find tab
+    CPluginClass *pClass = FindInstance(GetParent(hWnd));
+    if (!pClass)
+    {
+      return ::DefWindowProc(hWnd, message, wParam, lParam);
+    }
+
+    // Process message
+    switch (message)
+    {
+    case WM_SETCURSOR:
+      {
+        ::SetCursor(::LoadCursor(NULL, IDC_ARROW));
+        return TRUE;
+      }
+    case WM_PAINT:
+      {
+        PAINTSTRUCT ps;
+        HDC hDC = ::BeginPaint(hWnd, &ps);
+
+        AdblockPlus::Rectangle rcClient;
+        ::GetClientRect(hWnd, &rcClient);
+
+        int nDrawEdge = 0;
+
+        // Old Windows background drawing
+        if (pClass->m_hTheme == NULL)
+        {
+          ::FillRect(hDC, &rcClient, (HBRUSH)(COLOR_BTNFACE + 1));
+          ::DrawEdge(hDC, &rcClient, BDR_RAISEDINNER, BF_LEFT);
+
+          nDrawEdge = 3;
+          rcClient.left += 3;
+
+          ::DrawEdge(hDC, &rcClient, BDR_SUNKENOUTER, BF_RECT);
+        }
+        // Themed background drawing
+        else
+        {
+          // Draw background
+          if (pfnDrawThemeBackground)
           {
-            COLORREF clr = ::GetPixel(hDC, i + nWidth, j);
-
-            // Ignore black boxes (if source is obscured by other windows)
-            if (clr != -1 && (GetRValue(clr) > 8 || GetGValue(clr) > 8 || GetBValue(clr) > 8))
+            AdblockPlus::Rectangle rc = rcClient;
+            rc.right -= 2;
+            pfnDrawThemeBackground(pClass->m_hTheme, hDC, 0, 0, &rc, NULL);
+          }
+
+          // Copy separator picture to left side
+          int nHeight = rcClient.Height();
+          int nWidth = rcClient.Width() - 2;
+
+          for (int i = 0; i < 2; i++)
+          {
+            for (int j = 0; j < nHeight; j++)
             {
-              ::SetPixel(hDC, i, j, clr);
+              COLORREF clr = ::GetPixel(hDC, i + nWidth, j);
+
+              // Ignore black boxes (if source is obscured by other windows)
+              if (clr != -1 && (GetRValue(clr) > 8 || GetGValue(clr) > 8 || GetBValue(clr) > 8))
+              {
+                ::SetPixel(hDC, i, j, clr);
+              }
             }
           }
         }
-      }
-
-      // Draw icon
-      if (CPluginClient::GetInstance())
-      {
-        HICON hIcon = GetStatusBarIcon(pClass->GetTab()->GetDocumentUrl());
-
-        int offx = nDrawEdge;
-        if (hIcon)
-        {
-          //Get the RECT for the leftmost pane (the status text pane)
+
+        // Draw icon
+        if (CPluginClient::GetInstance())
+        {
+          HICON hIcon = GetStatusBarIcon(pClass->GetTab()->GetDocumentUrl());
+
+          int offx = nDrawEdge;
+          if (hIcon)
+          {
+            //Get the RECT for the leftmost pane (the status text pane)
+            RECT rect;
+            BOOL rectRes = ::SendMessage(pClass->m_hStatusBarWnd, SB_GETRECT, 0, (LPARAM)&rect);
+            ::DrawIconEx(hDC, 0, rect.bottom - rect.top - iconHeight, hIcon, iconWidth, iconHeight, NULL, NULL, DI_NORMAL);
+            offx += iconWidth;
+          }
+#ifdef _DEBUG
+          // Display version
+          HFONT hFont = (HFONT)::SendMessage(pClass->m_hStatusBarWnd, WM_GETFONT, 0, 0);
+          HGDIOBJ hOldFont = ::SelectObject(hDC, hFont);
+
+          AdblockPlus::Rectangle rcText = rcClient;
+          rcText.left += offx;
+          ::SetBkMode(hDC, TRANSPARENT);
+          ::DrawTextW(hDC, IEPLUGIN_VERSION, -1, &rcText, DT_WORD_ELLIPSIS | DT_LEFT | DT_SINGLELINE | DT_VCENTER);
+
+          ::SelectObject(hDC, hOldFont);
+#endif // _DEBUG
+        }
+
+        // Done!
+        EndPaint(hWnd, &ps);
+
+        return 0;
+      }
+
+    case WM_LBUTTONUP:
+    case WM_RBUTTONUP:
+      {
+        std::wstring url = pClass->GetBrowserUrl();
+        if (url != pClass->GetTab()->GetDocumentUrl())
+        {
+          pClass->GetTab()->SetDocumentUrl(url);
+        }
+
+        // Create menu
+        HMENU hMenu = pClass->CreatePluginMenu(url);
+        if (!hMenu)
+        {
+          return 0;
+        }
+
+        // Display menu
+        POINT pt;
+        ::GetCursorPos(&pt);
+
+        RECT rc;
+        ::GetWindowRect(hWnd, &rc);
+
+        if (rc.left >= 0 && rc.top >= 0)
+        {
+          pt.x = rc.left;
+          pt.y = rc.top;
+        }
+
+        pClass->DisplayPluginMenu(hMenu, -1, pt, TPM_LEFTALIGN | TPM_BOTTOMALIGN);
+        break;
+      }
+    case WM_DESTROY:
+      break;
+    case SC_CLOSE:
+      break;
+
+    case WM_UPDATEUISTATE:
+      {
+        CPluginTab* tab = GetTabForCurrentThread();
+        if (tab)
+        {
+          tab->OnActivate();
           RECT rect;
-          BOOL rectRes = ::SendMessage(pClass->m_hStatusBarWnd, SB_GETRECT, 0, (LPARAM)&rect);
-          ::DrawIconEx(hDC, 0, rect.bottom - rect.top - iconHeight, hIcon, iconWidth, iconHeight, NULL, NULL, DI_NORMAL);
-          offx += iconWidth;
-        }
-#ifdef _DEBUG
-        // Display version
-        HFONT hFont = (HFONT)::SendMessage(pClass->m_hStatusBarWnd, WM_GETFONT, 0, 0);
-        HGDIOBJ hOldFont = ::SelectObject(hDC,hFont);
-
-        AdblockPlus::Rectangle rcText = rcClient;
-        rcText.left += offx;
-        ::SetBkMode(hDC, TRANSPARENT);
-        ::DrawTextW(hDC, IEPLUGIN_VERSION, -1, &rcText, DT_WORD_ELLIPSIS|DT_LEFT|DT_SINGLELINE|DT_VCENTER);
-
-        ::SelectObject(hDC, hOldFont);
-#endif // _DEBUG
-      }
-
-      // Done!
-      EndPaint(hWnd, &ps);
-
-      return 0;
-    }
-
-  case WM_LBUTTONUP:
-  case WM_RBUTTONUP:
-    {
-      std::wstring url = pClass->GetBrowserUrl();
-      if (url != pClass->GetTab()->GetDocumentUrl())
-      {
-        pClass->GetTab()->SetDocumentUrl(url);
-      }
-
-      // Create menu
-      HMENU hMenu = pClass->CreatePluginMenu(url);
-      if (!hMenu)
-      {
-        return 0;
-      }
-
-      // Display menu
-      POINT pt;
-      ::GetCursorPos(&pt);
-
-      RECT rc;
-      ::GetWindowRect(hWnd, &rc);
-
-      if (rc.left >= 0 && rc.top >= 0)
-      {
-        pt.x = rc.left;
-        pt.y = rc.top;
-      }
-
-      pClass->DisplayPluginMenu(hMenu, -1, pt, TPM_LEFTALIGN|TPM_BOTTOMALIGN);
-    }
-    break;
-  case WM_DESTROY:
-    break;
-  case SC_CLOSE:
-    break;
-
-  case WM_UPDATEUISTATE:
-    {
-      CPluginTab* tab = GetTabCurrentThread();
-      if (tab)
-      {
-        tab->OnActivate();
+          GetWindowRect(pClass->m_hPaneWnd, &rect);
+          pClass->notificationMessage.MoveToCenter(rect);
+        }
+        if (LOWORD(wParam) == UIS_CLEAR)
+        {
+          pClass->notificationMessage.Hide();
+        }
+        break;
+      }
+    case WM_WINDOWPOSCHANGING:
+      {
         RECT rect;
         GetWindowRect(pClass->m_hPaneWnd, &rect);
-        pClass->notificationMessage.Move(rect.left + (rect.right - rect.left) / 2, rect.top + (rect.bottom - rect.top) / 2); 
-      }
-      if (LOWORD(wParam) == UIS_CLEAR)
-      {
-        pClass->notificationMessage.Hide();
-      }
-    }
-    break;
-  case WM_WINDOWPOSCHANGING:
-    {
-      RECT rect;
-      GetWindowRect(pClass->m_hPaneWnd, &rect);
-      if (pClass->notificationMessage.IsVisible())
-      {
-        pClass->notificationMessage.Move(rect.left + (rect.right - rect.left) / 2, rect.top + (rect.bottom - rect.top) / 2); 
-      }
-    }
-    break;
-  case WM_WINDOWPOSCHANGED:
-    {
-      WINDOWPOS* wndPos = reinterpret_cast<WINDOWPOS*>(lParam);
-      if (wndPos->flags & SWP_HIDEWINDOW)
-      {
-        pClass->notificationMessage.Hide();
-      }
-    }
-    break;
-  case WM_ALREADY_UP_TO_DATE:
-    {
-      Dictionary* dictionary = Dictionary::GetInstance();
-      std::wstring upToDateText = dictionary->Lookup("updater", "update-already-up-to-date-text");
-      std::wstring upToDateTitle = dictionary->Lookup("updater", "update-already-up-to-date-title");
-      pClass->notificationMessage.SetTextAndIcon(upToDateText, upToDateTitle, TTI_INFO);
-    }
-    break;
-  case WM_UPDATE_CHECK_ERROR:
-    {
-      Dictionary* dictionary = Dictionary::GetInstance();
-      std::wstring errorText = dictionary->Lookup("updater", "update-error-text");
-      std::wstring errorTitle = dictionary->Lookup("updater", "update-error-title");
-      pClass->notificationMessage.SetTextAndIcon(errorText, errorText, TTI_ERROR);
-    }
-    break;
-  case WM_DOWNLOADING_UPDATE:
-    {
-      Dictionary* dictionary = Dictionary::GetInstance();
-      std::wstring downloadingText = dictionary->Lookup("updater", "downloading-update-text");
-      std::wstring downloadingTitle = dictionary->Lookup("updater", "downloading-update-title");
-      pClass->notificationMessage.SetTextAndIcon(downloadingText, downloadingTitle, TTI_INFO);
-    }
-    break;
-  }
-
-  return DefWindowProc(hWnd, message, wParam, lParam);
+        if (pClass->notificationMessage.IsVisible())
+        {
+          pClass->notificationMessage.MoveToCenter(rect);
+        }
+        break;
+      }
+    case WM_WINDOWPOSCHANGED:
+      {
+        WINDOWPOS* wndPos = reinterpret_cast<WINDOWPOS*>(lParam);
+        if (wndPos->flags & SWP_HIDEWINDOW)
+        {
+          pClass->notificationMessage.Hide();
+        }
+        break;
+      }
+    case WM_ALREADY_UP_TO_DATE:
+      {
+        Dictionary* dictionary = Dictionary::GetInstance();
+        std::wstring upToDateText = dictionary->Lookup("updater", "update-already-up-to-date-text");
+        std::wstring upToDateTitle = dictionary->Lookup("updater", "update-already-up-to-date-title");
+        pClass->notificationMessage.SetTextAndIcon(upToDateText, upToDateTitle, TTI_INFO);
+        break;
+      }
+    case WM_UPDATE_CHECK_ERROR:
+      {
+        Dictionary* dictionary = Dictionary::GetInstance();
+        std::wstring errorText = dictionary->Lookup("updater", "update-error-text");
+        std::wstring errorTitle = dictionary->Lookup("updater", "update-error-title");
+        pClass->notificationMessage.SetTextAndIcon(errorText, errorTitle, TTI_ERROR);
+        break;
+      }
+    case WM_DOWNLOADING_UPDATE:
+      {
+        Dictionary* dictionary = Dictionary::GetInstance();
+        std::wstring downloadingText = dictionary->Lookup("updater", "downloading-update-text");
+        std::wstring downloadingTitle = dictionary->Lookup("updater", "downloading-update-title");
+        pClass->notificationMessage.SetTextAndIcon(downloadingText, downloadingTitle, TTI_INFO);
+        break;
+      }
+    }
+  }
+  catch (...)
+  {
+    // Suppress exception. Fall through to default handler.
+    DEBUG_GENERAL(L"CPluginClass::PaneWindowProc - exception");
+  }
+  return ::DefWindowProc(hWnd, message, wParam, lParam);
 }
 
 
 void CPluginClass::UpdateStatusBar()
 {
   DEBUG_GENERAL("*** Updating statusbar")
   if (m_hPaneWnd == NULL)
   {
     CreateStatusBarPane();
   }
@@ skipping 48 matching lines @@
   s_criticalSectionLocal.Unlock();
 
   return icon;
 }
 
 ATOM CPluginClass::GetAtomPaneClass()
 {
   return s_atomPaneClass;
 }