Noissue - Eliminate compile warnings in the plugin

src/plugin/PluginClass.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2015 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
@@ skipping 59 matching lines @@
  */
 namespace AdblockPlus
 {
   /**
     * Replacement for ATL type CRect.
     */
   class Rectangle
     : public RECT
   {
   public:
-    int Height() const
+    unsigned long Height() const
     {
-      return bottom - top;
+      if (bottom < top)
+      {
+        throw std::runtime_error("invariant violation: rectangle bottom < top");
+      }
+      return static_cast<unsigned long>(bottom - top);
     }
 
-    int Width() const
+    unsigned long Width() const
     {
-      return right - left;
+      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 = ";
@@ skipping 1471 matching lines @@
       break;
 
     case WM_UPDATEUISTATE:
       {
         CPluginTab* tab = GetTab(::GetCurrentThreadId());
         if (tab)
         {
           tab->OnActivate();
           RECT rect;
           GetWindowRect(pClass->m_hPaneWnd, &rect);
-          pClass->notificationMessage.Move(rect.left + (rect.right - rect.left) / 2, rect.top + (rect.bottom - rect.top) / 2);
+          pClass->notificationMessage.MoveToCenter(rect);
         }
         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);
+          pClass->notificationMessage.MoveToCenter(rect);
         }
         break;
       }
     case WM_WINDOWPOSCHANGED:
       {
         WINDOWPOS* wndPos = reinterpret_cast<WINDOWPOS*>(lParam);
         if (wndPos->flags & SWP_HIDEWINDOW)
         {
           pClass->notificationMessage.Hide();
         }
@@ skipping 92 matching lines @@
   s_criticalSectionLocal.Unlock();
 
   return icon;
 }
 
 ATOM CPluginClass::GetAtomPaneClass()
 {
   return s_atomPaneClass;
 }