Items Control should have a Transp. Background so it can be used as a Drop Target

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

@@ -79,6 +79,32 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 		}
 	}
 	
+	[ExtensionFor(typeof(ItemsControl))]
+	public sealed class TransparentControlsInstanceFactory : CustomInstanceFactory
+	{
+		Brush _transparentBrush = new SolidColorBrush(Colors.Transparent);
+		
+		/// <summary>
+		/// Creates an instance of the specified type, passing the specified arguments to its constructor.
+		/// </summary>
+		public override object CreateInstance(Type type, params object[] arguments)
+		{
+			object instance = base.CreateInstance(type, arguments);
+			Control control = instance as Control;
+			if (control != null && (
+				type == typeof(ItemsControl))) {
+				if (control.Background == null) {
+					control.Background = _transparentBrush;
+				}
+				
+				TypeDescriptionProvider provider = new DummyValueInsteadOfNullTypeDescriptionProvider(
+					TypeDescriptor.GetProvider(control), "Background", _transparentBrush);
+				TypeDescriptor.AddProvider(provider, control);
+			}
+			return instance;
+		}
+	}
+	
 	[ExtensionFor(typeof(Border))]
 	public sealed class BorderInstanceFactory : CustomInstanceFactory
 	{
@@ -104,119 +130,4 @@ namespace ICSharpCode.WpfDesign.Designer.Extensions
 			return instance;
 		}
 	}
-	
-	sealed class DummyValueInsteadOfNullTypeDescriptionProvider : TypeDescriptionProvider
-	{
-		// By using a TypeDescriptionProvider, we can intercept all access to the property that is
-		// using a PropertyDescriptor. WpfDesign.XamlDom uses a PropertyDescriptor for accessing
-		// properties (except for attached properties), so even DesignItemProperty/XamlProperty.ValueOnInstance
-		// will report null when the actual value is the dummy value.
-		
-		readonly string _propertyName;
-		readonly object _dummyValue;
-		
-		public DummyValueInsteadOfNullTypeDescriptionProvider(TypeDescriptionProvider existingProvider,
-		                                                      string propertyName, object dummyValue)
-			: base(existingProvider)
-		{
-			this._propertyName = propertyName;
-			this._dummyValue = dummyValue;
-		}
-		
-		public override ICustomTypeDescriptor GetTypeDescriptor(Type objectType, object instance)
-		{
-			return new ShadowTypeDescriptor(this, base.GetTypeDescriptor(objectType, instance));
-		}
-		
-		sealed class ShadowTypeDescriptor : CustomTypeDescriptor
-		{
-			readonly DummyValueInsteadOfNullTypeDescriptionProvider _parent;
-			
-			public ShadowTypeDescriptor(DummyValueInsteadOfNullTypeDescriptionProvider parent,
-			                            ICustomTypeDescriptor existingDescriptor)
-				: base(existingDescriptor)
-			{
-				this._parent = parent;
-			}
-			
-			public override PropertyDescriptorCollection GetProperties()
-			{
-				return Filter(base.GetProperties());
-			}
-			
-			public override PropertyDescriptorCollection GetProperties(Attribute[] attributes)
-			{
-				return Filter(base.GetProperties(attributes));
-			}
-			
-			PropertyDescriptorCollection Filter(PropertyDescriptorCollection properties)
-			{
-				PropertyDescriptor property = properties[_parent._propertyName];
-				if (property != null) {
-					if ((properties as System.Collections.IDictionary).IsReadOnly) {
-						properties = new PropertyDescriptorCollection(properties.Cast<PropertyDescriptor>().ToArray());
-					}
-					properties.Remove(property);
-					properties.Add(new ShadowPropertyDescriptor(_parent, property));
-				}
-				return properties;
-			}
-		}
-		
-		sealed class ShadowPropertyDescriptor : PropertyDescriptor
-		{
-			readonly DummyValueInsteadOfNullTypeDescriptionProvider _parent;
-			readonly PropertyDescriptor _baseDescriptor;
-			
-			public ShadowPropertyDescriptor(DummyValueInsteadOfNullTypeDescriptionProvider parent,
-			                                PropertyDescriptor existingDescriptor)
-				: base(existingDescriptor)
-			{
-				this._parent = parent;
-				this._baseDescriptor = existingDescriptor;
-			}
-			
-			public override Type ComponentType {
-				get { return _baseDescriptor.ComponentType; }
-			}
-			
-			public override bool IsReadOnly {
-				get { return _baseDescriptor.IsReadOnly; }
-			}
-			
-			public override Type PropertyType {
-				get { return _baseDescriptor.PropertyType; }
-			}
-			
-			public override bool CanResetValue(object component)
-			{
-				return _baseDescriptor.CanResetValue(component);
-			}
-			
-			public override object GetValue(object component)
-			{
-				object value = _baseDescriptor.GetValue(component);
-				if (value == _parent._dummyValue)
-					return null;
-				else
-					return value;
-			}
-			
-			public override void ResetValue(object component)
-			{
-				_baseDescriptor.SetValue(component, _parent._dummyValue);
-			}
-			
-			public override void SetValue(object component, object value)
-			{
-				_baseDescriptor.SetValue(component, value ?? _parent._dummyValue);
-			}
-			
-			public override bool ShouldSerializeValue(object component)
-			{
-				return _baseDescriptor.ShouldSerializeValue(component)
-					&& _baseDescriptor.GetValue(component) != _parent._dummyValue;
-			}
-		}
-	}
 }

src/AddIns/DisplayBindings/WpfDesign/WpfDesign/Project/DummyValueInsteadOfNullTypeDescriptionProvider.cs

@@ -0,0 +1,142 @@
+// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+// 
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System;
+using System.ComponentModel;
+using System.Linq;
+
+namespace ICSharpCode.WpfDesign
+{
+	/// <summary>
+	/// Description of DummyValueInsteadOfNullTypeDescriptionProvider.
+	/// </summary>
+	public sealed class DummyValueInsteadOfNullTypeDescriptionProvider : TypeDescriptionProvider
+	{
+		// By using a TypeDescriptionProvider, we can intercept all access to the property that is
+		// using a PropertyDescriptor. WpfDesign.XamlDom uses a PropertyDescriptor for accessing
+		// properties (except for attached properties), so even DesignItemProperty/XamlProperty.ValueOnInstance
+		// will report null when the actual value is the dummy value.
+		
+		readonly string _propertyName;
+		readonly object _dummyValue;
+		
+		public DummyValueInsteadOfNullTypeDescriptionProvider(TypeDescriptionProvider existingProvider,
+		                                                      string propertyName, object dummyValue)
+			: base(existingProvider)
+		{
+			this._propertyName = propertyName;
+			this._dummyValue = dummyValue;
+		}
+		
+		public override ICustomTypeDescriptor GetTypeDescriptor(Type objectType, object instance)
+		{
+			return new ShadowTypeDescriptor(this, base.GetTypeDescriptor(objectType, instance));
+		}
+		
+		sealed class ShadowTypeDescriptor : CustomTypeDescriptor
+		{
+			readonly DummyValueInsteadOfNullTypeDescriptionProvider _parent;
+			
+			public ShadowTypeDescriptor(DummyValueInsteadOfNullTypeDescriptionProvider parent,
+			                            ICustomTypeDescriptor existingDescriptor)
+				: base(existingDescriptor)
+			{
+				this._parent = parent;
+			}
+			
+			public override PropertyDescriptorCollection GetProperties()
+			{
+				return Filter(base.GetProperties());
+			}
+			
+			public override PropertyDescriptorCollection GetProperties(Attribute[] attributes)
+			{
+				return Filter(base.GetProperties(attributes));
+			}
+			
+			PropertyDescriptorCollection Filter(PropertyDescriptorCollection properties)
+			{
+				PropertyDescriptor property = properties[_parent._propertyName];
+				if (property != null) {
+					if ((properties as System.Collections.IDictionary).IsReadOnly) {
+						properties = new PropertyDescriptorCollection(properties.Cast<PropertyDescriptor>().ToArray());
+					}
+					properties.Remove(property);
+					properties.Add(new ShadowPropertyDescriptor(_parent, property));
+				}
+				return properties;
+			}
+		}
+		
+		sealed class ShadowPropertyDescriptor : PropertyDescriptor
+		{
+			readonly DummyValueInsteadOfNullTypeDescriptionProvider _parent;
+			readonly PropertyDescriptor _baseDescriptor;
+			
+			public ShadowPropertyDescriptor(DummyValueInsteadOfNullTypeDescriptionProvider parent,
+			                                PropertyDescriptor existingDescriptor)
+				: base(existingDescriptor)
+			{
+				this._parent = parent;
+				this._baseDescriptor = existingDescriptor;
+			}
+			
+			public override Type ComponentType {
+				get { return _baseDescriptor.ComponentType; }
+			}
+			
+			public override bool IsReadOnly {
+				get { return _baseDescriptor.IsReadOnly; }
+			}
+			
+			public override Type PropertyType {
+				get { return _baseDescriptor.PropertyType; }
+			}
+			
+			public override bool CanResetValue(object component)
+			{
+				return _baseDescriptor.CanResetValue(component);
+			}
+			
+			public override object GetValue(object component)
+			{
+				object value = _baseDescriptor.GetValue(component);
+				if (value == _parent._dummyValue)
+					return null;
+				else
+					return value;
+			}
+			
+			public override void ResetValue(object component)
+			{
+				_baseDescriptor.SetValue(component, _parent._dummyValue);
+			}
+			
+			public override void SetValue(object component, object value)
+			{
+				_baseDescriptor.SetValue(component, value ?? _parent._dummyValue);
+			}
+			
+			public override bool ShouldSerializeValue(object component)
+			{
+				return _baseDescriptor.ShouldSerializeValue(component)
+					&& _baseDescriptor.GetValue(component) != _parent._dummyValue;
+			}
+		}
+	}
+}

src/AddIns/DisplayBindings/WpfDesign/WpfDesign/Project/WpfDesign.csproj

@@ -73,6 +73,7 @@
     <Compile Include="Adorners\AdornerProvider.cs" />
     <Compile Include="Adorners\AdornerProviderClasses.cs" />
     <Compile Include="Adorners\RelativePlacement.cs" />
+    <Compile Include="DummyValueInsteadOfNullTypeDescriptionProvider.cs" />
     <Compile Include="ExtensionMethods.cs" />
     <Compile Include="Extensions\ExtensionAttribute.cs" />
     <Compile Include="Extensions\ExtensionInterfaces.cs" />