Refactor UI layout and data context management

- Replaced `Panel` with `ContentControl` in `ConductorView.axaml` for better layout handling.
- Changed root element from `Grid` to `StackPanel` in `TabView.axaml`, and updated data binding for `ItemsControl`.
- Added `DataContext` binding convention for `Panel` in `ConventionManager.cs` to enhance data context management.

Author: vb2ae

samples/features/Features.Avalonia/Views/ConductorView.axaml

@@ -31,16 +31,8 @@
             </ListBox.ItemTemplate>
         </ListBox>
 
-        <Panel DataContext="{Binding ActiveItem}" Grid.Row="2" Margin="40">
-            <TextBlock  Text="{Binding DisplayName}" FontSize="24" Foreground="Blue"/>
-            <ItemsControl ItemsSource="{Binding Messages}" Margin="30">
-                <ItemsControl.ItemTemplate>
-                    <DataTemplate>
-                        <TextBlock Text="{Binding}"/>
-                    </DataTemplate>
-                </ItemsControl.ItemTemplate>
-            </ItemsControl>
-        </Panel>
+        <ContentControl cal:View.Model="{Binding ActiveItem}" Grid.Row="2" Margin="40">
+        </ContentControl>
 
     </Grid>
 </UserControl>

samples/features/Features.Avalonia/Views/TabView.axaml

@@ -4,13 +4,14 @@
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
              mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
              x:Class="Features.CrossPlatform.Views.TabView">
-    <Grid>
+    <StackPanel>
+        <TextBlock Text="{Binding DisplayName}"></TextBlock>
         <ItemsControl ItemsSource="{Binding Messages}">
             <ItemsControl.ItemTemplate>
                 <DataTemplate>
-                    <TextBlock Text="{Binding DisplayName}"/>
+                        <TextBlock Text="{Binding}"/>
                 </DataTemplate>
             </ItemsControl.ItemTemplate>
         </ItemsControl>
-    </Grid>
+    </StackPanel>
 </UserControl>

src/Caliburn.Micro.Platform/ConventionManager.cs

@@ -341,6 +341,7 @@ static ConventionManager()
 #if AVALONIA
             AddElementConvention<UserControl>(UserControl.IsVisibleProperty, "DataContext", loadedEvent);
             AddElementConvention<ListBox>(ListBox.ItemsSourceProperty, "DataContext", loadedEvent);
+            AddElementConvention<Panel>(Panel.DataContextProperty, "DataContext", loadedEvent);
 #else
             AddElementConvention<UserControl>(UserControl.VisibilityProperty, "DataContext", loadedEvent);
 #endif