深入解析:打造自动消失的对话框

原理：使用Popup控件，并且设置Popup控件的位置居中。

1：新建自定义控件PopupBorder,作为Popup的child。代码如下：

    <Grid x:Name="LayoutRoot" >
        <!--<Border Background="#FFCC0D0D" BorderThickness="0" CornerRadius="5">-->
        <Border BorderThickness="0" CornerRadius="5">
            <Border.Background>
                <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
                    <GradientStop Color="#FF27A3D7" Offset="0.51"/>
                    <GradientStop Color="#FF76C2E1" Offset="0.004"/>
                    <GradientStop Color="#FF27A3D7" Offset="1"/>
                </LinearGradientBrush>
            </Border.Background>
            <Border.Effect>
                <DropShadowEffect BlurRadius="10" Color="#FFCC0D0D" ShadowDepth="0"/>
            </Border.Effect>
            <TextBlock x:Name="txtMessage" HorizontalAlignment="Center" Margin="10" VerticalAlignment="Center"
                       FontSize="28" Foreground="White" FontFamily="Comic Sans MS"
                       >This is a Simple Example</TextBlock>
        </Border>
    </Grid>
</UserControl>
</div>

新建PopupDemo页面，代码如下：