<Window
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"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:ei="http://schemas.microsoft.com/expression/2010/interactions"
x:Name="Window"
Title="Loading"
Width="640" Height="480" Background="{x:Null}" WindowStyle="None" AllowsTransparency="True" VerticalAlignment="Bottom" WindowStartupLocation="CenterScreen" WindowState="Maximized">
<Grid x:Name="LayoutRoot" Background="#4C000000">

    <Grid HorizontalAlignment="Center" VerticalAlignment="Center" Width="277" Height="277">
    <MediaElement x:Name="Loading" MediaEnded="Loading_MediaEnded" UnloadedBehavior="Manual"
    Source="Images/Loading.gif" LoadedBehavior="Play" Stretch="None" Clip="M0.5,19.5 C0.5,9.0065898 9.0065898,0.5 19.5,0.5 L257.5,0.5 C267.99341,0.5 276.5,9.0065898 276.5,19.5 L276.5,257.5 C276.5,267.99341 267.99341,276.5 257.5,276.5 L19.5,276.5 C9.0065898,276.5 0.5,267.99341 0.5,257.5 z"/>

    </Grid>

</Grid>

LoadingAnim loadingAnimation  = new LoadingAnim();
loadingAnimation.Owner = this;
loadingAnimation.Show();