monodevelop编译错误； 如果存在引用，为什么会丢失汇编引用？

Question

我从MonoDevelop创建了一个GTK＃2.0项目，它生成了两个文件：

Program.cs

using System;
using Gtk;

namespace Application
{
    class MainClass
    {
        public static void Main(string[] args)
        {
            Application.Init();
            MainWindow win = new MainWindow();
            win.Show();
            Application.Run();
        }
    }
}

MainWindow.cs：

using System;
using Gtk;

public partial class MainWindow : Gtk.Window
{
    public MainWindow() : base(Gtk.WindowType.Toplevel)
    {
        Build();
    }

    protected void OnDeleteEvent(object sender, DeleteEventArgs a)
    {
        Application.Quit();
        a.RetVal = true;
    }
}

我按下了“调试”按钮，未修改任何代码。 然后编译器打印此：

The type or namespace name `Init' does not exist in the namespace `Application'. Are you missing an assembly reference? (CS0234)
The type or namespace name `Run' does not exist in the namespace `Application'. Are you missing an assembly reference? (CS0234)
The type or namespace name `Quit' does not exist in the namespace `Application'. Are you missing an assembly reference? (CS0234)

我在“解决方案”选项卡上看到了“参考”列表，并且存在Gtk.Application.Init，Run，Quit。 那为什么会发生这个错误呢？

Answer 1

将Program.cs修改为：

using System;
using Gtk;

namespace Application
{
    class MainClass
    {
        public static void Main(string[] args)
        {
            Gtk.Application.Init();
            MainWindow win = new MainWindow();
            win.Show();
            Gtk.Application.Run();
        }
    }
}

修改MainWindow.cs为：

using System;
using Gtk;

public partial class MainWindow : Gtk.Window
{
    public MainWindow() : base(Gtk.WindowType.Toplevel)
    {
        Build();
    }

    protected void OnDeleteEvent(object sender, DeleteEventArgs a)
    {
        Gtk.Application.Quit();
        a.RetVal = true;
    }
}