WPF命令问题

Question

为什么命令控制总是被禁用，但命令可以执行？命令还可以使用 Alt + F4 运行

public static class CommandLibrary {
    static CommandLibrary() {
        ShutDownCommand = new RoutedUICommand("Exit", "Exit", typeof(CommandLibrary), new InputGestureCollection {new KeyGesture(Key.F4, ModifierKeys.Alt)});
    }

    public static RoutedUICommand ShutDownCommand { get; private set; }

    public static void BindCommands(Window hostWindow) {
        if (hostWindow == null)
            return;

        hostWindow.CommandBindings.Add(new CommandBinding(ShutDownCommand, OnShutDownCommandExecuted, OnShutDownCommandCanExecute));
    }

    private static void OnShutDownCommandExecuted(object sender, ExecutedRoutedEventArgs e) {
        MessageBox.Show("ShutDown Excuted!");
    }

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

<MenuItem Command="local:CommandLibrary.ShutDownCommand" />

Answer 1

通常发生这种情况是因为在设置了 Command 的控件范围内没有该命令的 CommandBinding。如果您在 CanExecute 处理程序中设置断点，MenuItem 是否会命中该断点？