feat: implement title bar and caption buttons.

demo/Ursa.Demo/Views/MainView.axaml

@@ -22,8 +22,7 @@
     <Panel>
         <Grid
             Classes.Blur="{Binding #host.HasModal}"
-            ColumnDefinitions="Auto, *"
-            RowDefinitions="Auto, *">
+            ColumnDefinitions="Auto, *" >
             <Grid.Styles>
                 <Style Selector="Grid.Blur">
                     <Setter Property="Effect" Value="blur(20)" />
@@ -31,7 +30,6 @@
             </Grid.Styles>
             <Border
                 Padding="8 4"
-                Grid.RowSpan="2"
                 VerticalAlignment="Stretch"
                 Theme="{DynamicResource CardBorder}">
                 <u:NavMenu Name="menu" ItemsSource="{Binding Menus.MenuItems}"
@@ -89,16 +87,9 @@
                     </u:NavMenu.Header>
                 </u:NavMenu>
             </Border>
-            <u:ThemeToggleButton
-                Grid.Row="0"
-                Grid.Column="1"
-                IsThreeState="True"
-                Mode="Controller"
-                HorizontalAlignment="Right" />
             <ContentControl
-                Grid.Row="1"
                 Grid.Column="1"
-                Margin="12"
+                Margin="12 36 12 12"
                 Content="{Binding Content}">
                 <ContentControl.ContentTemplate>
                     <converters:ViewLocator />