completed basic function

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

@@ -9,6 +9,8 @@ namespace HandyControl.Controls
 
         private SideMenuItem _selectedHeader;
 
+        private bool _isItemSelected;
+
         public SideMenu()
         {
             AddHandler(SideMenuItem.SelectedEvent, new RoutedEventHandler(SideMenuItemSelected));
@@ -27,17 +29,30 @@ namespace HandyControl.Controls
 
                     _selectedItem = item;
                     _selectedItem.IsSelected = true;
+                    _isItemSelected = true;
                 }
                 else
                 {
-                    if (_selectedHeader != null)
+                    if (!Equals(item, _selectedHeader))
                     {
-                        _selectedHeader.IsSelected = false;
+                        if (_selectedHeader != null)
+                        {
+                            _selectedHeader.IsSelected = false;
+                        }
+
+                        _selectedHeader = item;
+                        _selectedHeader.IsSelected = true;
                     }
 
-                    _selectedHeader = item;
-                    _selectedHeader.IsSelected = true;
-                    _selectedHeader.SelectDefaultItem(_selectedItem);
+                    if (_isItemSelected)
+                    {
+                        _isItemSelected = false;
+                    }
+                    else
+                    {
+                        _selectedHeader.SelectDefaultItem();
+                        _isItemSelected = false;
+                    }
                 }
             }
         }

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

@@ -72,20 +72,16 @@ namespace HandyControl.Controls
 
             if (_isMouseLeftButtonDown)
             {
-                if (!IsSelected)
-                {
-                    IsSelected = true;
-                    OnSelected(new RoutedEventArgs(SelectedEvent, this));
-                }
+                IsSelected = true;
+                OnSelected(new RoutedEventArgs(SelectedEvent, this));
                 _isMouseLeftButtonDown = false;
             }
         }
 
-        internal void SelectDefaultItem(SideMenuItem menuItem)
+        internal void SelectDefaultItem()
         {
             if (Role == SideMenuItemRole.Header && ItemsHost.Children.Count > 0)
             {
-                if (ItemsHost.Children.Contains(menuItem)) return;
                 var item = ItemsHost.Children.OfType<SideMenuItem>().FirstOrDefault();
                 if (item != null && !item.IsSelected)
                 {

src/Shared/HandyControl_Shared/Data/Enum/ExpandMode.cs

@@ -0,0 +1,25 @@
+namespace HandyControl.Data.Enum
+{
+    public enum ExpandMode
+    {
+        /// <summary>
+        ///     显示所有项，且不可折叠
+        /// </summary>
+        ShowAll,
+
+        /// <summary>
+        ///     最多只能显示一项，且不可折叠
+        /// </summary>
+        ShowOne,
+
+        /// <summary>
+        ///     类似ShowOne，但是控件的尺寸不随项的数量而改变
+        /// </summary>
+        Accordion,
+
+        /// <summary>
+        ///     没有任何限制
+        /// </summary>
+        Freedom
+    }
+}

src/Shared/HandyControl_Shared/HandyControl_Shared.projitems

@@ -112,6 +112,7 @@
     <Compile Include="$(MSBuildThisFileDirectory)Data\Enum\BadgeStatus.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Data\Enum\ChatMessageType.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Data\Enum\ChatRoleType.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Data\Enum\ExpandMode.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Data\Enum\InfoType.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Data\Enum\IpType.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Data\Enum\ResultType.cs" />

src/Shared/HandyControl_Shared/Themes/Styles/Base/SideMenuBaseStyle.xaml

@@ -28,7 +28,7 @@
                             <Setter TargetName="PresenterIcon" Property="Visibility" Value="Collapsed"/>
                         </Trigger>
                         <DataTrigger Binding="{Binding IsSelected,RelativeSource={RelativeSource AncestorType=controls:SideMenuItem}}" Value="True">
-                            <Setter Property="BorderBrush" Value="{DynamicResource DarkOpacityBrush}"/>
+                            <Setter Property="BorderBrush" Value="{DynamicResource BorderBrush}"/>
                         </DataTrigger>
                         <Trigger Property="IsSelected" Value="True">
                             <Setter Property="BorderBrush" Value="{DynamicResource PrimaryBrush}"/>
@@ -75,7 +75,7 @@
                         </Trigger>
                         <Trigger Property="IsSelected" Value="True">
                             <Setter TargetName="BorderBack" Property="BorderThickness" Value="4,0,0,0"/>
-                            <Setter TargetName="BorderBack" Property="BorderBrush" Value="{DynamicResource DarkOpacityBrush}"/>
+                            <Setter TargetName="BorderBack" Property="BorderBrush" Value="{DynamicResource BorderBrush}"/>
                             <Setter Property="TextElement.FontWeight" Value="Bold" TargetName="PresenterHeader"/>
                         </Trigger>
                         <Trigger SourceName="PanelHeader" Property="IsMouseOver" Value="true">