toast using a popup

ToastNotification.xaml

<UserControl x:Class="TheHub.Silverlight.Controls.ToastNotification"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
             x:Name="root">

    <Popup x:Name="NotificationPopup" IsHitTestVisible="False" >
        <VisualStateManager.VisualStateGroups>
            <VisualStateGroup x:Name="VisualStateGroup">
                <VisualStateGroup.Transitions >
                    <VisualTransition GeneratedDuration="5" To="Normal">
                    </VisualTransition>
                </VisualStateGroup.Transitions>
                <VisualState x:Name="Normal" >
                    <Storyboard x:Name="FaderStory">
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="LayoutRoot">
                            <EasingDoubleKeyFrame KeyTime="0" Value="0"/>
                            <EasingDoubleKeyFrame KeyTime="0:0:1" Value="1"/>
                        </DoubleAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>
                <VisualState x:Name="Hidden" >
                    <Storyboard x:Name="HideFaderStory">
                        <DoubleAnimationUsingKeyFrames Storyboard.TargetProperty="(UIElement.Opacity)" Storyboard.TargetName="LayoutRoot">
                            <EasingDoubleKeyFrame KeyTime="0" Value="1"/>
                        </DoubleAnimationUsingKeyFrames>
                    </Storyboard>
                </VisualState>
            </VisualStateGroup>
        </VisualStateManager.VisualStateGroups>

        <Border BorderBrush="DarkRed" BorderThickness="2">
            <Grid x:Name="LayoutRoot" Background="AliceBlue" Height="45" Width="200" VerticalAlignment="Center" HorizontalAlignment="Center" MouseLeftButtonUp="LayoutRoot_MouseLeftButtonUp">
                <StackPanel Orientation="Vertical">
                    <StackPanel Orientation="Horizontal" Visibility="{Binding ElementName=root, Path=FromVisibility}">
                        <TextBlock FontSize="12">From:</TextBlock>
                        <TextBlock FontSize="12" x:Name="txtFrom"></TextBlock>
                    </StackPanel>
                    
                    <TextBlock x:Name="MessageTB" VerticalAlignment="Center" FontSize="14"  Foreground="Black" Text="Your text here" TextWrapping="Wrap" />
                    <TextBlock x:Name="MessagePaused" HorizontalAlignment="Center" VerticalAlignment="Center"  Foreground="Black" Text="Click to pause." TextAlignment="Center" />
                </StackPanel>
            </Grid>
        </Border>
    </Popup>
</UserControl>

ToastNotification.xaml.cs

using System;
using System.Windows;
using System.Windows.Threading;

namespace TheHub.Silverlight.Controls
{
    public partial class ToastNotification 
    {
        private readonly DispatcherTimer timer;

        public ToastNotification(double timespan)
        {
            PauseMessage = "";
            TextMsg = "";
            InitializeComponent();
            timer = new DispatcherTimer();
            timer.Interval = TimeSpan.FromSeconds(timespan);
            timer.Tick += TimerTick;
            LayoutRoot.Width = 200;
            LayoutRoot.Height = 200;
            NotificationPopup.HorizontalOffset = Application.Current.Host.Content.ActualWidth / Application.Current.Host.Content.ZoomFactor - 200;
            NotificationPopup.VerticalOffset = Application.Current.Host.Content.ActualHeight / Application.Current.Host.Content.ZoomFactor - 200;
        }

        public string TextMsg { get; set; }

        public string PauseMessage { get; set; }

        public static readonly DependencyProperty FromVisibilityProperty = DependencyProperty.Register(
            "FromVisibility", typeof(Visibility), typeof(ToastNotification), new PropertyMetadata(Visibility.Visible));

        public Visibility FromVisibility
        {
            get { return (Visibility) GetValue(FromVisibilityProperty); }
            set { SetValue(FromVisibilityProperty, value); }
        }

        /// <summary>
        /// public constructor
        /// </summary>
        /// <param name="timespan"></param>
        /// <returns></returns>
        public static ToastNotification CreateToast(double timespan)
        {
            return new ToastNotification(timespan);
        }

        /// <summary>
        /// Diaplay the Toast
        /// </summary>
        /// <param name="message"></param>
        public void ShowMessage(string message, string from)
        {
            PauseMessage = "Click to pause.";
            MessagePaused.Text = PauseMessage;

            txtFrom.Text = from;
            TextMsg = message;
            MessageTB.Text = TextMsg;

            NotificationPopup.IsOpen = true;

            if (timer.IsEnabled)
            {
                timer.Stop();
            }
            timer.Start();

            VisualStateManager.GoToState(this, "Normal", false);
        }

        private void TimerTick(object sender, EventArgs e)
        {
            VisualStateManager.GoToState(this, "Hidden", false);
            NotificationPopup.IsOpen = false;
            timer.Stop();
        }

        /// <summary>
        /// Click to pause or close toast
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void LayoutRoot_MouseLeftButtonUp(object sender, System.Windows.Input.MouseButtonEventArgs e)
        {
            if (timer.IsEnabled)
            {
                timer.Stop();
                PauseMessage = "Message held - Click here to close.";
                MessagePaused.Text = PauseMessage;
            }
            else
            {
                VisualStateManager.GoToState(this, "Hidden", false);
                NotificationPopup.IsOpen = false;
                PauseMessage = "Click to pause.";
            }

        }

    }
}

Known issue - if a toast appears and the window is resized, subsequent toast are misplaced.