Silverlight Windows Phone 7 - 使用硬件后退按钮后按钮单击事件丢失

Question

在 Windows phone 7 Silverlight 项目中，当折叠包含按钮的面板，然后使用硬件后退按钮返回(再次将可见性设置为可见)时，FIRST 单击事件丢失。

这让我发疯了一段时间。

这是一种简单的重现方法，启动一个新的 Wp7 silverlight 应用程序，然后在 xaml 上添加两个带有按钮的内容面板。

    <Grid x:Name="ContentPanel" Grid.Row="1" Visibility="Visible">
        <Button Content="Change Visibility" Click="ChangeButton_Click"/>
    </Grid>
    <Grid x:Name="ContentPanel2" Grid.Row="1" Visibility="Collapsed">
        <Button Content="Back" Click="BackButton_Click"/>
    </Grid>

后面的代码有两个按钮和硬件后退按钮的处理程序，可以简单地在两个面板之间切换可见性。

    public MainPage()
    {
        InitializeComponent();
        BackKeyPress += new EventHandler<System.ComponentModel.CancelEventArgs>(MainPage_BackKeyPress);
    }

    void MainPage_BackKeyPress(object sender, System.ComponentModel.CancelEventArgs e)
    {
        if (ContentPanel2.Visibility == Visibility.Visible)
        {
            ContentPanel.Visibility = Visibility.Visible;
            ContentPanel2.Visibility = Visibility.Collapsed;
            e.Cancel = true;
        }
    }

    private void ChangeButton_Click(object sender, RoutedEventArgs e)
    {
        ContentPanel.Visibility = Visibility.Collapsed;
        ContentPanel2.Visibility = Visibility.Visible;
    }

    private void BackButton_Click(object sender, RoutedEventArgs e)
    {
        ContentPanel.Visibility = Visibility.Visible;
        ContentPanel2.Visibility = Visibility.Collapsed;
    }

现在奇怪的事情是:

如果您使用屏幕上的后退按钮切换工作正常

如果使用硬件后退按钮切换回来，那么之后的FIRST click事件就会丢失!

这发生在模拟器和真实设备上。

这是一个错误吗？或者我做错了什么？

Answer 1

有人叫 Fendors(谢谢!)在 app hub forums 上回答了我的问题.他没有找到它发生的原因，但找到了一个解决方法:

"I didn't figure out fully what is happening when the hardware back button is clicked, but did find a workaround. I was initially thinking maybe there was some sort of focus issue and found that if you set the content panel from visible to collapsed to visible, it puts it into a good state"

void MainPage_BackKeyPress(object sender, System.ComponentModel.CancelEventArgs e) 
        { 
            if (ContentPanel2.Visibility == Visibility.Visible) 
            { 
                ContentPanel2.Visibility = Visibility.Collapsed; 
                ContentPanel.Visibility = Visibility.Visible; 
                ContentPanel.Visibility = Visibility.Collapsed; 
                ContentPanel.Visibility = Visibility.Visible; 

                e.Cancel = true; 
            } 
        }