sa/Stars Assistant/Views/MainWindow.axaml

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:vm="using:StarsAssistant.ViewModels"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="StarsAssistant.Views.MainWindow"
        x:DataType="vm:MainWindowViewModel"
        Icon="/Assets/avalonia-logo.ico"
        Title="GetStartedApp">

        <!-- Icon="/Assets/avalonia-logo.ico" -->

    <Design.DataContext>
        <!-- This only sets the DataContext for the previewer in an IDE,
             to set the actual DataContext for runtime, set the DataContext property in code (look at App.axaml.cs) -->
        <vm:MainWindowViewModel/>
    </Design.DataContext>

    <TabControl>
        <TabItem Header="Home">
            <StackPanel>
                <Border Margin="5" CornerRadius="10" Background="LightBlue">
                    <TextBlock Margin="5" FontSize="24" HorizontalAlignment="Center" Text="{Binding Greeting}"></TextBlock>
                </Border>
                <Grid ShowGridLines="True" Margin="5" ColumnDefinitions="120, 100" RowDefinitions="Auto, Auto, Auto">  
                    <Label Grid.Row="0" Grid.Column="0" Margin="10">Celsius</Label>
                    <TextBox Grid.Row="0" Grid.Column="1" Margin="0 5" Text="0" Name="celsius"/>
                    <Label Grid.Row="1" Grid.Column="0" Margin="10">Fahrenheit</Label>
                    <TextBox Grid.Row="1"  Grid.Column="1" Margin="0 5" Text="0" Name="fahrenheit"/>
                    <Button Grid.Row="2" Grid.Column="1" Margin="0 5" Click="ButtonClicked">Calculate</Button>
                </Grid>
            </StackPanel>
        </TabItem>
        <TabItem Header="DataGrid">
            <DataGrid ItemsSource="{Binding Planets}"   
                AutoGenerateColumns="True" IsReadOnly="True" 
                GridLinesVisibility="All"
                FrozenColumnCount="1"
                BorderThickness="1" BorderBrush="Gray">
            </DataGrid>
        </TabItem>
        <TabItem Header="ScrollViewer">
            <ScrollViewer>
                <ItemsControl ItemsSource="{Binding Planets}">
                    <ItemsControl.ItemTemplate>
                        <DataTemplate DataType="vm:PlanetViewModel">
                            <Grid ColumnDefinitions="200, 100, 50">
                                <TextBlock Grid.Column="0" Text="{Binding Name}"/>
                                <TextBlock Grid.Column="1" Text="{Binding Owner}"/>
                                <TextBlock Grid.Column="2" Text="{Binding Value}"/>
                            </Grid>
                        </DataTemplate>
                    </ItemsControl.ItemTemplate>
                </ItemsControl>
            </ScrollViewer>
        </TabItem>
    </TabControl>
</Window>