在XAML里面引用枚举值的注意点

本来以为XAML的扩展x:Static很简单，但在实际的编程过程中，遇到了不小的麻烦，看如下代码（其中，VM名字空间指向正确），我试图将枚举值FetchAndShowMode赋给CommandParameter，可是却编译出错：Cannot find the type 'MoviesVM.FetchAndShowMode'. Note that type names are case sensitive.

    partial class MoviesVM
    {
        public enum FetchAndShowMode
        {
            None,        // Needn't refetch the data
            Recent,      // Fetch recent recorded movies
            All,         // Fetch all the movies
            ByKeyword,   // Fetch the movies by name
            Default,     // Fetch the movies by defalut settings
            NotVerified, // Fetch not verified movies
            Special      // Reserve for future use
        };

<ribbon:RibbonButton LargeImageSource="Resources\Images\Ribbon\RecentMovies.png" Label="近期影片"
                     Command="local:MainWindow.ViewMovies" 
                     CommandParameter="{x:Static vm:MoviesVM.FetchAndShowMode.Recent}" />

网上查了下，发现，假如是内嵌的类型，WPF需要你使用“+”来分割，所以应该写成vm:MoviesVM+FetchAndShowMode。但是，编译仍然不过，说：Only public or internal classes can be used within markup. 'FetchAndShowMode' type is not public or internal. 但是FetchAndShowMode明明是public的啊！自己查了下原因，应该是编译器比较傻，MovieVM类是internal的，FetchAndShowMode是public就不认，假如把他们俩同时改成public或者都是internal的就可以了，这个也不知道是不是一个bug。。。

最后，能通过编译并正常运行的代码如下：

    public partial class MoviesVM
    {
        public enum FetchAndShowMode
        {
            None,        // Needn't refetch the data
            Recent,      // Fetch recent recorded movies
            All,         // Fetch all the movies
            ByKeyword,   // Fetch the movies by name
            Default,     // Fetch the movies by defalut settings
            NotVerified, // Fetch not verified movies
            Special      // Reserve for future use
        };

<ribbon:RibbonButton LargeImageSource="Resources\Images\Ribbon\RecentMovies.png" Label="近期影片"
                     Command="local:MainWindow.ViewMovies" 
                     CommandParameter="{x:Static vm:MoviesVM+FetchAndShowMode.Recent}" />