Do not crash on opening document when embedded.

- VERBESSERT: Kein Absturz mehr, wenn das Demo-Dokument innerhalb der ZAA geöffnet wird (Exception ID 65a5c34e).

zaaReloaded2/Ribbon.cs

@@ -16,12 +16,9 @@
  * limitations under the License.
  */
 using System;
-using System.Collections.Generic;
 using System.IO;
-using System.Linq;
 using System.Reflection;
 using System.Runtime.InteropServices;
-using System.Text;
 using System.Windows;
 using System.Drawing;
 using System.Windows.Resources;
@@ -33,7 +30,6 @@ using zaaReloaded2.Formatter;
 using zaaReloaded2.Controller;
 using Word = Microsoft.Office.Interop.Word;
 using Bovender.Mvvm.Actions;
-using Bovender.Mvvm.Messaging;
 
 // TODO:  Follow these steps to enable the Ribbon (XML) item:
 
@@ -114,7 +110,7 @@ namespace zaaReloaded2
                             Globals.ThisAddIn.Application.Selection);
                         break;
                     case "zrlDemo":
-                        Demo.Demo.OpenDemoDocument();
+                        DoLoadDemo();
                         break;
                     default:
                         throw new InvalidOperationException("No operation defined for " + control.Id);
@@ -230,6 +226,47 @@ namespace zaaReloaded2
             vm.InjectInto<SettingsRepositoryView>().ShowDialog();
         }
 
+        /// <summary>
+        /// Loads the embedded demo document.
+        /// </summary>
+        /// <remarks>
+        /// If Word is running in an embedded environment (e.g. in the ZAA),
+        /// adding a document causes a COMException. Unfortunately, it is
+        /// not trivial to test if Word is running embedded, so we use a
+        /// try...catch structure and catch all COMExceptions. The error
+        /// message might be not quite right if the exception was caused by
+        /// a different problem.
+        /// See http://davecra.com/2013/04/10/how-to-determine-if-an-excel-workbook-is-embedded-and-more
+        /// </remarks>
+        void DoLoadDemo()
+        {
+            try
+            {
+                Demo.Demo.OpenDemoDocument();
+            }
+            catch (System.Runtime.InteropServices.COMException e)
+            {
+                // HRESULT comparison according to http://stackoverflow.com/a/1426198/270712
+                // Fix for exception ID 65a5c34e
+                if (e.ErrorCode == unchecked((int)0x800A11FD))
+                {
+                    NotificationAction a = new NotificationAction();
+                    a.Caption = "Kann Demo-Dokument nicht laden";
+                    a.Message = "Das Demo-Dokument kann nicht geladen werden, "
+                        + "wenn Word in der Zentralen Arztbriefablage ausgeführt wird.\r"
+                        + "Bitte Word als eigenständige Anwendung starten und dann "
+                        + "noch einmal versuchen.";
+                    a.OkButtonLabel = "Schließen";
+                    a.Invoke();
+                }
+                else
+                {
+                    throw;
+                }
+            }
+
+        }
+
         public void Application_WindowSelectionChange(Microsoft.Office.Interop.Word.Selection Sel)
         {
             _ribbon.Invalidate();