fix insertion of ="" with x:Key or other special completion items

src/AddIns/BackendBindings/XamlBinding/XamlBinding/XamlCompletionItemList.cs

@@ -60,10 +60,9 @@ namespace ICSharpCode.XamlBinding
 					context.EndOffset++;
 				}
 				
-				if (item is XamlCompletionItem) {
+				if (item is XamlCompletionItem && !item.Text.EndsWith(":", StringComparison.Ordinal)) {
 					XamlCompletionItem cItem = item as XamlCompletionItem;
 					
-					if (cItem.Entity is IProperty || cItem.Entity is IEvent) {
 					if (xamlContext.Description == XamlContextDescription.InTag) {
 						context.Editor.Document.Insert(context.EndOffset, "=\"\"");
 						context.CompletionCharHandled = context.CompletionChar == '=';
@@ -95,7 +94,6 @@ namespace ICSharpCode.XamlBinding
 							new XamlCodeCompletionBinding().CtrlSpace(context.Editor);
 					}
 				}
-				}
 				
 				if (item is NewEventCompletionItem) {
 					CreateEventHandlerCode(xamlContext, item as NewEventCompletionItem);