Clear message boxes in windowmanager cleanup (Fixes #1496)

apps/openmw/mwgui/messagebox.cpp

@@ -25,6 +25,23 @@ namespace MWGui
         }
     }
 
+    void MessageBoxManager::clear()
+    {
+        delete mInterMessageBoxe;
+        mInterMessageBoxe = NULL;
+
+        std::vector<MessageBox*>::iterator it(mMessageBoxes.begin());
+        for (; it != mMessageBoxes.end(); ++it)
+        {
+            if (*it == mStaticMessageBox)
+                mStaticMessageBox = NULL;
+            delete *it;
+        }
+        mMessageBoxes.clear();
+
+        mLastButtonPressed = -1;
+    }
+
     void MessageBoxManager::onFrame (float frameDuration)
     {
         std::vector<MessageBox*>::iterator it;

apps/openmw/mwgui/messagebox.hpp

@@ -30,6 +30,9 @@ namespace MWGui
             bool createInteractiveMessageBox (const std::string& message, const std::vector<std::string>& buttons);
             bool isInteractiveMessageBox ();
 
+            /// Remove all message boxes
+            void clear();
+
             bool removeMessageBox (MessageBox *msgbox);
             void setMessageBoxSpeed (int speed);
 

apps/openmw/mwgui/windowmanagerimp.cpp

@@ -1502,6 +1502,7 @@ namespace MWGui
     {
         mMap->clear();
         mQuickKeysMenu->clear();
+        mMessageBoxManager->clear();
 
         mTrainingWindow->resetReference();
         mDialogueWindow->resetReference();