How to display Object with sub-class in PropertyGrid

Question

I'm going to use PropertyGrid to show my Objects. Here is the info class. The Info class has some properties which is composed of the class type. However, the sub-class doesn't show the properties. Do you have any idea?

Code snippet:

using System.ComponentModel;
using System.Windows.Forms;

namespace WindowsFormsApplication_propertyGrid
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            info _in = new info();
            this.propertyGrid1.SelectedObject = _in;
        }
    }

    [DefaultPropertyAttribute("Name")]
    [TypeConverter(typeof(ExpandableObjectConverter))]
    public class info
    {
        private int _id;
        [CategoryAttribute("Defaults")]
        public int Id
        {
            get { return _id; }
            set { _id = value; }
        }

        private string _name;
        [CategoryAttribute("Defaults")]
        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }

        private DoublePoint _resultMarkPos;
        [CategoryAttribute("Results")]
        [TypeConverter(typeof(ExpandableObjectConverter))]
        public DoublePoint ResultMarkPos
        {
            get { return _resultMarkPos; }
            set { _resultMarkPos = value; }
        }

        public struct DoublePoint
        {
            public double x, y;
        }

        private subInfo1 _sub1;
        [CategoryAttribute("SubInfo")]
        [TypeConverter(typeof(ExpandableObjectConverter))]
        public subInfo1 SubInfo1
        {
            get { return _sub1; }
            set { _sub1 = value; }
        }

        private subInfo2 _sub2;
        [CategoryAttribute("SubInfo2")]
        [TypeConverter(typeof(ExpandableObjectConverter))]
        public subInfo2 SubInfo2
        {
            get { return _sub2; }
            set { _sub2 = value; }
        }

        public info()
        {
            this._id = 0;
            this._name = "info";

            this._resultMarkPos.x = 0;
            this._resultMarkPos.y = 0;

            this._sub1 = new subInfo1
            {
                Id = 11,
                Name = "sub11",
            };

            this._sub2 = new subInfo2
            {
                Id = 22,
                Name = "sub22",
            };
        }
    }

    public class subInfo1
    {
        private int _id;
        public int Id
        {
            get { return _id; }
            set { _id = value; }
        }

        private string _name;
        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }

        public subInfo1()
        {
            this._id = 0;
            this._name = "sub1";
        }
    }

    public class subInfo2
    {
        private int _id;
        public int Id 
        {
            get { return _id; }
            set { _id = value; }
        }

        private string _name;
        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }

        public subInfo2()
        {
            this._id = 0;
            this._name = "sub2";
        }
    }
}

Edited However, struct case doesn't effect for [TypeConverter(typeof(ExpandableObjectConverter))] attribute. Do you have any idea ?

private DoublePoint _resultMarkPos;
[CategoryAttribute("Results")]
[TypeConverter(typeof(ExpandableObjectConverter))]
public DoublePoint ResultMarkPos
{
            get { return _resultMarkPos; }
            set { _resultMarkPos = value; }
}

public struct DoublePoint
{
        public double x, y;
}

Answer 1

You need to use TypeConverter:

    private subInfo1 _sub1;        
    [CategoryAttribute("SubInfo")]
    [TypeConverter(typeof(ExpandableObjectConverter))]
    public subInfo1 SubInfo1
    {
        get { return _sub1; }
        set { _sub1 = value; }
    }
    private subInfo2 _sub2;
    [CategoryAttribute("SubInfo2")]
    [TypeConverter(typeof(ExpandableObjectConverter))]
    public subInfo2 SubInfo2
    {
        get { return _sub2; }
        set { _sub2 = value; }
    }