WPF 上下文菜单命令绑定已禁用

Question

我有一个按钮和一个上下文菜单绑定到同一个命令，当我启动应用程序时，按钮被启用，但上下文菜单项没有（正如我所说，它们绑定到同一个命令）。仅当我单击按钮后，上下文菜单项才会启用。有人知道为什么吗？

这就是行为。

这是 XAML：

<Window.CommandBindings>
    <CommandBinding Command="local:LocalCommandManager.ShowDialogCommand" CanExecute="CanExecuteShowDialogCommand" Executed="ShowDialogCommandExecuted" />
    <CommandBinding Command="local:LocalCommandManager.DontShowDialogCommand" CanExecute="CanExecuteDontShowDialogCommand" Executed="DontShowDialogCommandExecuted" />
</Window.CommandBindings>
<Window.ContextMenu>
    <ContextMenu>
        <MenuItem Command="local:LocalCommandManager.ShowDialogCommand" />
        <MenuItem Command="local:LocalCommandManager.DontShowDialogCommand" />
    </ContextMenu>
</Window.ContextMenu>
<Grid Background="Red">
    <Button Command="local:LocalCommandManager.ShowDialogCommand" Content="Show Dialog" HorizontalAlignment="Center" VerticalAlignment="Center" Padding="6" />
</Grid>

谢谢！

编辑：

命令代码：

public static class LocalCommandManager
{
    private static object syncRoot = new object();

    private static RoutedUICommand _showDialogCommand;
    public static RoutedUICommand ShowDialogCommand
    {
        get
        {
            lock (syncRoot)
            {
                if (_showDialogCommand == null)
                    _showDialogCommand = new RoutedUICommand("Show Dialog", "ShowDialogCommand", typeof(LocalCommandManager));
                return _showDialogCommand;
            }
        }
    }
}

命令事件处理程序（在 MainWindow.xaml.cs 中）：

private void CanExecuteShowDialogCommand(object sender, CanExecuteRoutedEventArgs e)
{
    e.CanExecute = true;
}

private void ShowDialogCommandExecuted(object sender, ExecutedRoutedEventArgs e)
{
    MessageBox.Show("Dialog");
}