support for .NET framework 3.5

Still have bugs

Net35/HandyControl_Net35/Controls/Button/ContextMenuToggleButton.cs

@@ -0,0 +1,31 @@
+using System.Windows.Controls;
+using System.Windows.Controls.Primitives;
+
+
+namespace HandyControl.Controls
+{
+    /// <summary>
+    ///     带上下文菜单的切换按钮
+    /// </summary>
+    public class ContextMenuToggleButton : ToggleButton
+    {
+        public ContextMenu Menu { get; set; }
+
+        protected override void OnClick()
+        {
+            base.OnClick();
+            if (Menu != null)
+            {
+                if (IsChecked == true)
+                {
+                    Menu.PlacementTarget = this;
+                    Menu.IsOpen = true;
+                }
+                else
+                {
+                    Menu.IsOpen = false;
+                }
+            }
+        }
+    }
+}