completed the branch

src/Shared/HandyControl_Shared/Controls/SideMenu/SideMenu.cs

@@ -1,6 +1,7 @@
-using System.Windows;
+using System;
+using System.Linq;
+using System.Windows;
 using HandyControl.Data;
-using HandyControl.Data.Enum;
 
 namespace HandyControl.Controls
 {
@@ -15,6 +16,22 @@ namespace HandyControl.Controls
         public SideMenu()
         {
             AddHandler(SideMenuItem.SelectedEvent, new RoutedEventHandler(SideMenuItemSelected));
+
+            Loaded += (s, e) => Init();
+        }
+
+        protected override void Refresh()
+        {
+            base.Refresh();
+
+            Init();
+        }
+
+        private void Init()
+        {
+            if (ItemsHost == null) return;
+
+            OnExpandModeChanged(ExpandMode);
         }
 
         private void SideMenuItemSelected(object sender, RoutedEventArgs e)
@@ -23,6 +40,8 @@ namespace HandyControl.Controls
             {
                 if (item.Role == SideMenuItemRole.Item)
                 {
+                    if (Equals(item, _selectedItem)) return;
+
                     if (_selectedItem != null)
                     {
                         _selectedItem.IsSelected = false;
@@ -30,6 +49,10 @@ namespace HandyControl.Controls
 
                     _selectedItem = item;
                     _selectedItem.IsSelected = true;
+                    RaiseEvent(new FunctionEventArgs<object>(SelectionChangedEvent, this)
+                    {
+                        Info = e.OriginalSource
+                    });
                     _isItemSelected = true;
                 }
                 else
@@ -38,20 +61,36 @@ namespace HandyControl.Controls
                     {
                         if (_selectedHeader != null)
                         {
+                            if (ExpandMode == ExpandMode.Freedom && item.ItemsHost.IsVisible && !_isItemSelected)
+                            {
+                                item.IsSelected = false;
+                                SwitchPanelArea(item);
+                                return;
+                            }
+
                             _selectedHeader.IsSelected = false;
-                            SwitchPanelArea(_selectedHeader);
+                            if (ExpandMode != ExpandMode.Freedom)
+                            {
+                                SwitchPanelArea(_selectedHeader);
+                            }
                         }
 
                         _selectedHeader = item;
                         _selectedHeader.IsSelected = true;
                         SwitchPanelArea(_selectedHeader);
                     }
+                    else if (ExpandMode == ExpandMode.Freedom && !_isItemSelected)
+                    {
+                        _selectedHeader.IsSelected = false;
+                        SwitchPanelArea(_selectedHeader);
+                        _selectedHeader = null;
+                    }
 
                     if (_isItemSelected)
                     {
                         _isItemSelected = false;
                     }
-                    else
+                    else if(_selectedHeader != null)
                     {
                         _selectedHeader.SelectDefaultItem();
                         _isItemSelected = false;
@@ -67,6 +106,7 @@ namespace HandyControl.Controls
                 case ExpandMode.ShowAll:
                     return;
                 case ExpandMode.ShowOne:
+                case ExpandMode.Freedom:
                 case ExpandMode.Accordion:
                     oldItem.SwitchPanelArea(oldItem.IsSelected);
                     break;
@@ -78,12 +118,72 @@ namespace HandyControl.Controls
         protected override bool IsItemItsOwnContainerOverride(object item) => item is SideMenuItem;
 
         public static readonly DependencyProperty ExpandModeProperty = DependencyProperty.Register(
-            "ExpandMode", typeof(ExpandMode), typeof(SideMenu), new PropertyMetadata(default(ExpandMode)));
+            "ExpandMode", typeof(ExpandMode), typeof(SideMenu), new PropertyMetadata(default(ExpandMode), OnExpandModeChanged));
+
+        private static void OnExpandModeChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+        {
+            var ctl = (SideMenu) d;
+            var v = (ExpandMode) e.NewValue;
+
+            if (ctl.ItemsHost == null)
+            {
+                return;
+            }
+
+            ctl.OnExpandModeChanged(v);
+        }
+
+        private void OnExpandModeChanged(ExpandMode mode)
+        {
+            if (mode == ExpandMode.ShowAll)
+            {
+                ShowAll();
+            }
+            else if (mode == ExpandMode.ShowOne)
+            {
+                var sideMenuItem = ItemsHost.Children.OfType<SideMenuItem>().FirstOrDefault(item => item.IsSelected);
+                ShowSelectedOne(sideMenuItem);
+            }
+        }
 
         public ExpandMode ExpandMode
         {
             get => (ExpandMode) GetValue(ExpandModeProperty);
             set => SetValue(ExpandModeProperty, value);
         }
+
+        public static readonly DependencyProperty PanelAreaLengthProperty = DependencyProperty.Register(
+            "PanelAreaLength", typeof(double), typeof(SideMenu), new PropertyMetadata(double.NaN));
+
+        public double PanelAreaLength
+        {
+            get => (double) GetValue(PanelAreaLengthProperty);
+            set => SetValue(PanelAreaLengthProperty, value);
+        }
+
+        private void ShowAll()
+        {
+            foreach (var sideMenuItem in ItemsHost.Children.OfType<SideMenuItem>())
+            {
+                sideMenuItem.SwitchPanelArea(true);
+            }
+        }
+
+        private void ShowSelectedOne(SideMenuItem item)
+        {
+            foreach (var sideMenuItem in ItemsHost.Children.OfType<SideMenuItem>())
+            {
+                sideMenuItem.SwitchPanelArea(Equals(sideMenuItem, item));
+            }
+        }
+
+        public static readonly RoutedEvent SelectionChangedEvent = EventManager.RegisterRoutedEvent(
+            "SelectionChanged", RoutingStrategy.Bubble, typeof(EventHandler<FunctionEventArgs<object>>), typeof(SideMenu));
+
+        public event EventHandler<FunctionEventArgs<object>> SelectionChanged
+        {
+            add => AddHandler(SelectionChangedEvent, value);
+            remove => RemoveHandler(SelectionChangedEvent, value);
+        }
     }
 }