Primary Selection but only when multiple Items

Extension Server should be Reapplied on Selection changed

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

@@ -161,6 +161,13 @@ namespace ICSharpCode.WpfDesign
 			for (int i = 0; i < _extensionServers.Length; i++) {
 				if (_extensionServers[i] == server) {
 					bool shouldApply = server.ShouldApplyExtensions(this);
+
+					if (server.ShouldBeReApplied() && shouldApply && shouldApply == _extensionServerIsApplied[i])
+					{
+						_extensionServerIsApplied[i] = false;
+						ApplyUnapplyExtensionServer(extensionManager, false, server);
+					}
+
 					if (shouldApply != _extensionServerIsApplied[i]) {
 						_extensionServerIsApplied[i] = shouldApply;
 						ApplyUnapplyExtensionServer(extensionManager, shouldApply, server);

src/AddIns/DisplayBindings/WpfDesign/WpfDesign/Project/Extensions/ExtensionServer.cs

@@ -74,6 +74,14 @@ namespace ICSharpCode.WpfDesign.Extensions
 		/// </summary>
 		public abstract bool ShouldApplyExtensions(DesignItem extendedItem);
 		
+		// <summary>
+		/// Set if the Extension Server should be reaplied (For multiple Selection extension Server for Example!)
+		/// </summary>
+		public virtual bool ShouldBeReApplied() 
+		{
+			return false;
+		}
+		
 		/// <summary>
 		/// Create an extension of the specified type.
 		/// Is called by the ExtensionManager.

src/AddIns/DisplayBindings/WpfDesign/WpfDesign/Project/Extensions/SelectionExtensionServer.cs

@@ -121,6 +121,11 @@ namespace ICSharpCode.WpfDesign.Extensions
 			ReapplyExtensions(this.Services.Selection.SelectedItems);
 		}
 		
+		public override bool ShouldBeReApplied()
+		{
+			return true;
+		}
+		
 		/// <summary>
 		/// Gets if the item is in the secondary selection.
 		/// </summary>