我之前开发一个软件 winMarkdown，这个软件在关闭须要提示用户还没有保存东西。须要保存。假设用户选择退出，那么把数据存放。

在Metro程序中，没有传统的窗体，当我们要用须要交互的消息提示时，在Win8时代。引入了一个MessageDialog来代替经常使用的MessageBox。

我在MainPage。挂起App.Current.Suspending += suspend;

        private async void suspend(object sender, Windows.ApplicationModel.SuspendingEventArgs e)
        {
            SuspendingDeferral deferral = e.SuspendingOperation.GetDeferral();
            MessageDialog message_dialog = new MessageDialog("当前还在执行，确定退出", "退出");
            message_dialog.Commands.Add(new UICommand("确定", cmd => { }, "退出"));
            message_dialog.Commands.Add(new UICommand("取消", cmd => { }));
            message_dialog.DefaultCommandIndex = 0;
            message_dialog.CancelCommandIndex = 1;
            IUICommand result = await message_dialog.ShowAsync();
            if (result.Id as string == "退出")
            {

            }
            deferral.Complete();
        }

SuspendingDeferral deferral = e.SuspendingOperation.GetDeferral();挂起还要做。直到deferral.Complete();

            MessageDialog message_dialog = new MessageDialog("当前还在执行，确定退出", "退出");
            message_dialog.Commands.Add(new UICommand("确定", cmd => { }, "退出"));
            message_dialog.Commands.Add(new UICommand("取消", cmd => { }));

两个button。一个确定，一个取消。能够UICommand ID作为点击后，是哪个button点击

MessageDialog.DefaultCommandIndex按ESC选择button
MessageDialog.CancelCommandIndex按enterbutton

            IUICommand result = await message_dialog.ShowAsync();
            if (result.Id as string == "退出")
            {

            }

程序要调试挂起。须要生命周期，点击挂起

我们按enter就会点击确定

而我们对于MessageDialog功能还是认为不够，ContentDialog能够定义复杂的Xaml自己定义

我们把MessageDialog换ContentDialog

            ContentDialog content_dialog = new ContentDialog()
            {
                Title = "退出",
                Content = "当前还在执行。确定退出",
                PrimaryButtonText = "确定",
                SecondaryButtonText = "取消",
                FullSizeDesired = true,
            };

            content_dialog.PrimaryButtonClick += (_s, _e) => { };

            await content_dialog.ShowAsync();

<UserControl
    x:Class="produproperty.content"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:produproperty"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="300"
    d:DesignWidth="400">

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition></RowDefinition>
            <RowDefinition></RowDefinition>
        </Grid.RowDefinitions>
        <TextBlock Grid.Row="0" Text="当前还在执行，确定退出"></TextBlock>
        <CheckBox Grid.Row="1" Content="保存"></CheckBox>
    </Grid>
</UserControl>

            ContentDialog content_dialog = new ContentDialog()
            {
                Title = "退出",
                Content = new content(),
                PrimaryButtonText = "确定",
                SecondaryButtonText = "取消",
                FullSizeDesired = false,
            };

            content_dialog.PrimaryButtonClick += (_s, _e) => { };

            await content_dialog.ShowAsync();

參见：
http://www.cnblogs.com/TianFang/p/4857205.html