Avalonia/src/Windows/Perspex.Designer/InProcDesigner/InProcDesignerView.xaml

<UserControl x:Class="Perspex.Designer.InProcDesigner.InProcDesignerView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
             xmlns:appHost="clr-namespace:Perspex.Designer.AppHost"
             xmlns:system="clr-namespace:System;assembly=mscorlib"
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300" d:DataContext="{d:DesignInstance appHost:HostedAppModel}">
    <DockPanel>
        <StackPanel Orientation="Horizontal" DockPanel.Dock="Bottom">
            <ComboBox ItemsSource="{Binding AvailableScalingFactors}" SelectedItem="{Binding CurrentScalingFactor, Mode=TwoWay}">
                <ComboBox.ItemTemplate>
                    <DataTemplate DataType="{x:Type system:Double}">
                        <TextBlock><Run Text="{Binding .}"/>00%</TextBlock>
                    </DataTemplate>
                </ComboBox.ItemTemplate>
            </ComboBox>
            <Border x:Name="ErrorPanel" BorderBrush="Red" BorderThickness="3" Padding="3">
                <StackPanel   Orientation="Horizontal">
                    <TextBlock Text="{Binding Error}" FontSize="16"/>
                    <TextBlock x:Name="DetailsBlock" FontSize="16">
                <Run> (</Run><Hyperlink Click="Hyperlink_OnClick">View details</Hyperlink><Run>)</Run>
                    </TextBlock>
                </StackPanel>
            </Border>
        </StackPanel>
        <WindowsFormsHost x:Name="WindowHostControl"/>
    </DockPanel>
</UserControl>