Prevent message box crashes due to corrupted or missing data dir.

Delay factories debug tests after all the subsystems and resource paths are added.
Register MessageBox object factory.

Source/Engine/Engine/Engine.cpp

@@ -157,13 +157,6 @@ bool Engine::Initialize(const VariantMap& parameters)
         RegisterGraphicsLibrary(context_);
     }
 
-    // In debug mode, check now that all factory created objects can be created without crashing
-    #ifdef _DEBUG
-    const HashMap<ShortStringHash, SharedPtr<ObjectFactory> >& factories = context_->GetObjectFactories();
-    for (HashMap<ShortStringHash, SharedPtr<ObjectFactory> >::ConstIterator i = factories.Begin(); i != factories.End(); ++i)
-        SharedPtr<Object> object = i->second_->CreateObject();
-    #endif
-
     // Start logging
     Log* log = GetSubsystem<Log>();
     if (log)
@@ -309,6 +302,13 @@ bool Engine::Initialize(const VariantMap& parameters)
         timeOut_ = GetParameter(parameters, "TimeOut", 0).GetInt() * 1000000LL;
     #endif
 
+    // In debug mode, check now that all factory created objects can be created without crashing
+    #ifdef _DEBUG
+    const HashMap<ShortStringHash, SharedPtr<ObjectFactory> >& factories = context_->GetObjectFactories();
+    for (HashMap<ShortStringHash, SharedPtr<ObjectFactory> >::ConstIterator i = factories.Begin(); i != factories.End(); ++i)
+        SharedPtr<Object> object = i->second_->CreateObject();
+    #endif
+
     frameTimer_.Reset();
 
     initialized_ = true;

Source/Engine/UI/MessageBox.cpp

@@ -37,13 +37,21 @@ namespace Urho3D
 {
 
 MessageBox::MessageBox(Context* context, const String& messageString, const String& titleString, XMLFile* layoutFile, XMLFile* styleFile) :
-    Object(context)
+    Object(context),
+    titleText_(0),
+    messageText_(0),
+    okButton_(0)
 {
     // If layout file is not given, use the default message box layout
     if (!layoutFile)
     {
         ResourceCache* cache = GetSubsystem<ResourceCache>();
         layoutFile = cache->GetResource<XMLFile>("UI/MessageBox.xml");
+        if (!layoutFile)
+        {
+            LOGERROR("Could not find default message box layout file: UI/MessageBox.xml");
+            return;
+        }
     }
 
     UI* ui = GetSubsystem<UI>();
@@ -70,7 +78,9 @@ MessageBox::MessageBox(Context* context, const String& messageString, const Stri
         }
         else
             LOGWARNING("Instantiating a modal window in headless mode!");
+
         window->SetModal(true);
+        SubscribeToEvent(window, E_MODALCHANGED, HANDLER(MessageBox, HandleMessageAcknowledged));
     }
 
     // Bind the buttons (if any in the loaded UI layout) to event handlers
@@ -86,13 +96,17 @@ MessageBox::MessageBox(Context* context, const String& messageString, const Stri
     Button* closeButton = dynamic_cast<Button*>(window_->GetChild("CloseButton", true));
     if (closeButton)
         SubscribeToEvent(closeButton, E_RELEASED, HANDLER(MessageBox, HandleMessageAcknowledged));
-
-    SubscribeToEvent(window_, E_MODALCHANGED, HANDLER(MessageBox, HandleMessageAcknowledged));
 }
 
 MessageBox::~MessageBox()
 {
-    window_->Remove();
+    if (window_)
+        window_->Remove();
+}
+
+void MessageBox::RegisterObject(Context* context)
+{
+    context->RegisterFactory<MessageBox>();
 }
 
 void MessageBox::SetTitle(const String& text)

Source/Engine/UI/MessageBox.h

@@ -42,6 +42,8 @@ public:
     MessageBox(Context* context, const String& messageString = String::EMPTY, const String& titleString = String::EMPTY, XMLFile* layoutFile = 0, XMLFile* styleFile = 0);
     /// Destruct.
     virtual ~MessageBox();
+    /// Register object factory.
+    static void RegisterObject(Context* context);
 
     /// Set title text. No-ops if there is no title text element.
     void SetTitle(const String& text);

Source/Engine/UI/UI.cpp

@@ -36,6 +36,7 @@
 #include "ListView.h"
 #include "Log.h"
 #include "Matrix3x4.h"
+#include "MessageBox.h"
 #include "Profiler.h"
 #include "Renderer.h"
 #include "ResourceCache.h"
@@ -1412,6 +1413,7 @@ void RegisterUILibrary(Context* context)
     Menu::RegisterObject(context);
     DropDownList::RegisterObject(context);
     FileSelector::RegisterObject(context);
+    MessageBox::RegisterObject(context);
     ToolTip::RegisterObject(context);
 }