<Window.Triggers>

    <EventTrigger RoutedEvent="Window.Loaded" >

        <BeginStoryboard>

            <Storyboard>

                <DoubleAnimation Duration="00:00:01" Storyboard.TargetProperty="Opacity" From="0" To="1" />

            </Storyboard>

        </BeginStoryboard>

    </EventTrigger>

</Window.Triggers>

<Window.Resources>

    <Storyboard x:Key="showMe">

        <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility">

            <DiscreteObjectKeyFrame KeyTime="0:0:0" Value="{x:Static Visibility.Visible}"/>

        </ObjectAnimationUsingKeyFrames>

        <DoubleAnimation Storyboard.TargetProperty="Opacity" Duration="0:0:1" To="0.75"/>

    </Storyboard>

    <Storyboard x:Key="hideMe">

    <DoubleAnimation Storyboard.TargetProperty="Opacity" Duration="0:0:1" To="0.0"/>

    <ObjectAnimationUsingKeyFrames Storyboard.TargetProperty="Visibility">

        <DiscreteObjectKeyFrame KeyTime="0:0:2" Value="{x:Static Visibility.Hidden}"/>

    </ObjectAnimationUsingKeyFrames>

</Storyboard>

</Window.Resources>

public new void Show()

{

    (FindResource("showMe") as System.Windows.Media.Animation.Storyboard).Begin(this);

}

public new void Hide()

{

    (FindResource("hideMe") as System.Windows.Media.Animation.Storyboard).Begin(this);

}