A WPF ErrorBox

ErrorBox.xaml

<Window.Resources>
    <BooleanToVisibilityConverter x:Key="BooleanToVisibility" />       <!-- System.Windows.Controls. -->
</Windown.Resources>
<Grid>
   <Grid.RowDefinitions>
      <RowDefinition Height="auto" />
      <RowDefinition Height="200*" />
      <RowDefinition Height="auto" />
    </Grid.RowDefinitions>

 ...
 
 <Grid x:Name="ErrorBoxSection" Grid.Row="2"  Margin="20"
              Visibility="{Binding HasError, Converter={StaticResource BooleanToVisibility}}">
            <Border BorderBrush="Black" BorderThickness="1" Background="White" d:IsHidden="True">
                <Border.Effect>
                    <DropShadowEffect ShadowDepth="2"/>
                </Border.Effect>
            </Border>

            <Border BorderBrush="DarkRed" BorderThickness=".5"
                x:Name="BorderError">
                <DockPanel>
                    <Button DockPanel.Dock="Top" HorizontalAlignment="Right" Command="{Binding ClearError}"
                        Margin="0,4,4,0"
                        BorderThickness="0"
                        Background="Transparent"
                        >
                        <Image Height="16" Width="16" Source="Assets/Close.png"/>
                    </Button>
                    <TextBlock  x:Name="ErrorBox" TextWrapping="Wrap" Margin="12, -12, 12, 12" Foreground="Red" Text="{Binding Error}">
                        <TextBlock.ContextMenu>
                            <ContextMenu>
                                <MenuItem Command="{Binding ErrorCopyToClipboard}" Header="Copy To Clipboard">
                                    <MenuItem.Icon>
                                        <Image Source="assets/check_green.png" Height="16"/>
                                    </MenuItem.Icon>
                                </MenuItem>
                                <MenuItem Command="{Binding ClearError}" Header="Close">
                                    <MenuItem.Icon>
                                        <Image Source="assets/close.png" Height="16"/>
                                    </MenuItem.Icon>
                                </MenuItem>
                            </ContextMenu>
                        </TextBlock.ContextMenu>
                    </TextBlock>
                </DockPanel>
            </Border>
        </Grid>
    </Grid>

MainWindow.cs

using Microsoft.Expression.Interactivity.Core;

...
    
VM.ErrorCopyToClipboard = new ActionCommand((o) =>
{
    if (!string.IsNullOrEmpty(VM.Error))
        Clipboard.SetText(VM.Error);
});

VM.cs

using System.ComponentModel;
using System.Runtime.CompilerServices;
using Microsoft.Expression.Interactivity.Core;

public class MainVM : INotifiedPropertyChanged
{

private string _Error;

public string Error
{
    get => _Error;
    set { _Error = value; OnPropertyChanged(nameof(Error)); OnPropertyChanged(nameof(HasError)); }
}

public bool HasError => !string.IsNullOrEmpty(Error);

// Install-Package System.Windows.Interactivity.WPF  for ICommand
public ICommand ClearError => new ActionCommand(() => { Error = string.Empty; });
public ICommand ErrorCopyToClipboard { get; set; }

 /// <summary>
 /// Event raised when a property changes.
 /// </summary>
 public event PropertyChangedEventHandler PropertyChanged;

 /// <summary>
 /// Raises the PropertyChanged event.
 /// </summary>
 /// <param name="propertyName">The name of the property that has changed.</param>
 protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = "")
    => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

}
}

Assets used

• check_green.png

• close.png

Misc gifs for use in other projects to show running.