added Ueb04 Csharp

and fixed problems

ADIS_Csharp/ADIS_Csharp.sln

@@ -11,6 +11,8 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Sync-Ueb02-Latch", "Sync-Ue
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Sync-Ueb03-WaitPool", "Sync-Ueb03-WaitPool\Sync-Ueb03-WaitPool.csproj", "{6041729C-8528-49A7-B335-1720B46DEFD1}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Sync-Ueb04-NestedMonitor", "Sync-Ueb04-NestedMonitor\Sync-Ueb04-NestedMonitor.csproj", "{839AB456-68F3-4ABC-A0EE-95F08FEFC033}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -33,6 +35,10 @@ Global
 		{6041729C-8528-49A7-B335-1720B46DEFD1}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{6041729C-8528-49A7-B335-1720B46DEFD1}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{6041729C-8528-49A7-B335-1720B46DEFD1}.Release|Any CPU.Build.0 = Release|Any CPU
+		{839AB456-68F3-4ABC-A0EE-95F08FEFC033}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{839AB456-68F3-4ABC-A0EE-95F08FEFC033}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{839AB456-68F3-4ABC-A0EE-95F08FEFC033}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{839AB456-68F3-4ABC-A0EE-95F08FEFC033}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE

ADIS_Csharp/Sync-Ueb04-NestedMonitor/BlackHole.cs

@@ -7,14 +7,10 @@ namespace Sync_Ueb04_NestedMonitor
         private NotifyingQueue<String> queue = new NotifyingQueue<String>();
 
         public void Put(String thing) {
-            lock (this) {
+            queue.Enqueue(thing);
-                queue.Enqueue(thing);
-            }
         }
         public String Get() {
-            lock (this) {
+            return queue.Dequeue();
-                return queue.Dequeue();
-            }
         }
     }
 }

ADIS_Csharp/Sync-Ueb04-NestedMonitor/NotifyingQueue.cs

@@ -20,7 +20,7 @@ namespace Sync_Ueb04_NestedMonitor
 
         public T Dequeue() {
             lock (this) {
-                if (head == tail) {
+                while (head == tail) {
                     Monitor.Wait(this);
                 }
                 tail++;