添加项目文件。

Dragablz/Dragablz/Converters/ShowDefaultCloseButtonConverter.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Globalization;
+using System.Windows;
+using System.Windows.Data;
+
+namespace Dragablz.Converters
+{
+    public class ShowDefaultCloseButtonConverter : IMultiValueConverter
+    {
+        /// <summary>
+        /// [0] is owning tabcontrol ShowDefaultCloseButton value.
+        /// [1] is owning tabcontrol FixedHeaderCount value.
+        /// [2] is item LogicalIndex
+        /// </summary>
+        /// <param name="values"></param>
+        /// <param name="targetType"></param>
+        /// <param name="parameter"></param>
+        /// <param name="culture"></param>
+        /// <returns></returns>
+        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
+        {
+            return ((values[0] == DependencyProperty.UnsetValue ? false : (bool)values[0]) && 
+                    (values[2] == DependencyProperty.UnsetValue ? 0 : (int)values[2]) >= 
+                    (values[1] == DependencyProperty.UnsetValue ? 0 : (int)values[1])) ? Visibility.Visible : Visibility.Collapsed;
+        }
+
+        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
+        {
+            return null;            
+        }
+    }
+}