Fix Default Initializer

- Fix Problems with nested TextBlocks (Text was removed when it was set)
- Fix that not every ContentControl can have a String as Content (for Example Zoom Control in Extended WPF Toolkit)

src/AddIns/DisplayBindings/WpfDesign/WpfDesign.Designer/Project/Extensions/Initializers.cs

@@ -15,13 +15,55 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions.Initializers
 	{
 		public override void InitializeDefaults(DesignItem item)
 		{
-			DesignItemProperty contentProperty = item.Properties["Content"];
-			if (contentProperty.ValueOnInstance == null) {
-				contentProperty.SetValue(item.ComponentType.Name);
+            //Not every Content Control can have a text as Content (e.g. ZoomBox of WPF Toolkit)
+		    if (item.Component is Button)
+		    {
+				DesignItemProperty contentProperty = item.Properties["Content"];
+		        if (contentProperty.ValueOnInstance == null)
+		        {
+					contentProperty.SetValue(item.ComponentType.Name);
+				}
 			}
+
+		    DesignItemProperty verticalAlignmentProperty = item.Properties["VerticalAlignment"];
+            if (verticalAlignmentProperty.ValueOnInstance == null)
+            {
+                verticalAlignmentProperty.SetValue(VerticalAlignment.Center);
+            }
+
+            DesignItemProperty horizontalAlignmentProperty = item.Properties["HorizontalAlignment"];
+            if (horizontalAlignmentProperty.ValueOnInstance == null)
+            {
+                horizontalAlignmentProperty.SetValue(HorizontalAlignment.Center);
+            }
 		}
 	}
 
+	[ExtensionFor(typeof(TextBlock))]
+    public class TextBlockInitializer : DefaultInitializer
+    {
+        public override void InitializeDefaults(DesignItem item)
+        {
+            DesignItemProperty textProperty = item.Properties["Text"];
+            if (textProperty.ValueOnInstance == null || textProperty.ValueOnInstance.ToString() == "")
+            {
+                textProperty.SetValue(item.ComponentType.Name);
+            }
+
+            DesignItemProperty verticalAlignmentProperty = item.Properties["VerticalAlignment"];
+            if (verticalAlignmentProperty.ValueOnInstance == null)
+            {
+                verticalAlignmentProperty.SetValue(VerticalAlignment.Center);
+            }
+
+            DesignItemProperty horizontalAlignmentProperty = item.Properties["HorizontalAlignment"];
+            if (horizontalAlignmentProperty.ValueOnInstance == null)
+            {
+                horizontalAlignmentProperty.SetValue(HorizontalAlignment.Center);
+            }
+        }
+	}
+    
 	[ExtensionFor(typeof(HeaderedContentControl), OverrideExtension = typeof(ContentControlInitializer))]
 	public class HeaderedContentControlInitializer : DefaultInitializer
 	{