Popup p = new Popup();
p.Child = new Border() { Width 100, Height 20}

<Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="108,103,0,0" Name="Button1" VerticalAlignment="Top" Width="75">

            <Button.Resources>

                <Storyboard x:Name="myStoryboard">

                    <!-- Blur the Button and then animate back to normal. -->

                    <DoubleAnimation

                        Storyboard.TargetName="myBlurBitmapEffect"

                        Storyboard.TargetProperty="Radius"

                        From="0" To="40" Duration="0:0:1"

                        AutoReverse="True" />

                </Storyboard>

            </Button.Resources>

            <Button.Effect>

                <BlurEffect x:Name="myBlurBitmapEffect" Radius="0"></BlurEffect>

            </Button.Effect>

        </Button>