feat: fix various nav menu layout issue.

demo/Ursa.Demo/Pages/NavMenuDemo.axaml

@@ -38,6 +38,7 @@
             Theme="{DynamicResource CardBorder}">
             <u:NavMenu
                 Name="menu"
+                ExpandWidth="400"
                 HeaderBinding="{Binding Header}"
                 IconBinding="{Binding IconIndex}"
                 IsHorizontalCollapsed="{Binding #collapse.IsChecked, Mode=OneWay}"

demo/Ursa.Demo/Views/MainView.axaml

@@ -35,6 +35,7 @@
                 VerticalAlignment="Stretch"
                 Theme="{DynamicResource CardBorder}">
                 <u:NavMenu Name="menu" ItemsSource="{Binding Menus.MenuItems}"
+                           ExpandWidth="300"
                            CommandBinding="{Binding ActivateCommand}"
                            HeaderBinding="{Binding}"
                            IconBinding="{Binding MenuHeader}">
@@ -58,7 +59,7 @@
                     </u:NavMenu.IconTemplate>
                     <u:NavMenu.HeaderTemplate>
                         <DataTemplate x:DataType="vm:MenuItemViewModel">
-                            <StackPanel Orientation="Horizontal" MinWidth="240">
+                            <StackPanel Orientation="Horizontal">
                                 <TextBlock HorizontalAlignment="Left" Text="{Binding MenuHeader}" />
                                 <u:Badge
                                     Margin="8,0,0,0"

src/Ursa.Themes.Semi/Controls/NavMenu.axaml

@@ -16,10 +16,10 @@
                     <ContentPresenter Content="{TemplateBinding Header}" DockPanel.Dock="Top" />
                     <ContentPresenter Content="{TemplateBinding Footer}" DockPanel.Dock="Bottom" />
                     <ScrollViewer
-                        HorizontalAlignment="Center"
+                        HorizontalAlignment="Stretch"
                         HorizontalScrollBarVisibility="Disabled"
                         AllowAutoHide="True"
-                        Theme="{DynamicResource StaticScrollViewer}"
+                        
                         VerticalScrollBarVisibility="Auto">
                         <ScrollViewer.Styles>
                             <Style Selector="ScrollViewer /template/ ScrollBar">
@@ -39,9 +39,12 @@
                 </DockPanel>
             </ControlTemplate>
         </Setter>
+        <Style Selector="^:not(:horizontal-collapsed)">
+            <Setter Property="Width" Value="{Binding $self.ExpandWidth}"></Setter>
+        </Style>
         <Style Selector="^:horizontal-collapsed">
-            <Setter Property="Width" Value="{x:Static x:Double.NaN}" />
+            <Setter Property="Width" Value="{Binding $self.CollapseWidth}" />
-            <Setter Property="HorizontalAlignment" Value="Left" />
+            <Setter Property="Grid.IsSharedSizeScope" Value="False"></Setter>
         </Style>
     </ControlTheme>
 
@@ -51,6 +54,7 @@
                 Name="PART_Border"
                 Grid.Row="0"
                 MinHeight="32"
+                HorizontalAlignment="Stretch"
                 Background="{TemplateBinding u:NavMenuItem.Background}"
                 CornerRadius="4"
                 Cursor="Hand">
@@ -164,7 +168,7 @@
             <Setter Property="Background" Value="{DynamicResource NavigationMenuItemPointeroverBackground}" />
         </Style>
         <Style Selector="^:horizontal-collapsed:first-level">
-            <Setter Property="HorizontalAlignment" Value="Left" />
+            <Setter Property="HorizontalAlignment" Value="Stretch" />
             <Style Selector="^ /template/ Border#PART_Border">
                 <Setter Property="ToolTip.Tip" >
                     <Template>
@@ -172,7 +176,7 @@
                     </Template>
                 </Setter>
                 <Setter Property="ToolTip.ShowDelay" Value="0" />
-                <Setter Property="HorizontalAlignment" Value="Left" />
+                <Setter Property="HorizontalAlignment" Value="Stretch" />
             </Style>
             <Style Selector="^ /template/ Border#PART_Border:pointerover">
                 <Setter Property="Background" Value="{DynamicResource NavigationMenuItemPointeroverBackground}" />
@@ -191,16 +195,15 @@
             <Style Selector="^ /template/ ItemsPresenter#PART_ItemsPresenter">
                 <Setter Property="IsVisible" Value="False" />
             </Style>
-            <Style Selector="^ /template/ Grid#PART_RootGrid">
-                <Setter Property="HorizontalAlignment" Value="Left" />
-            </Style>
-
         </Style>
         <Style Selector="^:horizontal-collapsed:not(:first-level)">
             <Style Selector="^ /template/ PathIcon#PART_ExpanderIcon">
                 <Setter Property="RenderTransform" Value="rotate(-90deg)" />
             </Style>
         </Style>
+        <Style Selector="^:horizontal-collapsed:first-level">
+            <Setter Property="Grid.IsSharedSizeScope" Value="True"></Setter>
+        </Style>
         <Style Selector="^[IsSeparator=True]">
             <Setter Property="Template">
                 <ControlTemplate>

src/Ursa/Controls/NavMenu/NavMenu.cs

@@ -129,6 +129,24 @@ public class NavMenu: ItemsControl
         set => SetValue(FooterProperty, value);
     }
 
+    public static readonly StyledProperty<double> ExpandWidthProperty = AvaloniaProperty.Register<NavMenu, double>(
+        nameof(ExpandWidth), double.NaN);
+
+    public double ExpandWidth
+    {
+        get => GetValue(ExpandWidthProperty);
+        set => SetValue(ExpandWidthProperty, value);
+    }
+
+    public static readonly StyledProperty<double> CollapseWidthProperty = AvaloniaProperty.Register<NavMenu, double>(
+        nameof(CollapseWidth), double.NaN);
+
+    public double CollapseWidth
+    {
+        get => GetValue(CollapseWidthProperty);
+        set => SetValue(CollapseWidthProperty, value);
+    }
+
     public static readonly AttachedProperty<bool> CanToggleProperty =
         AvaloniaProperty.RegisterAttached<NavMenu, InputElement, bool>("CanToggle");