c# - TypeConverter for a List of Objects -

i'm trying create windows form uses property grid display list of objects. right have few classes. first one, displaycontainer, holds list of objects , instance of acts selected object property grid

    [typeconverter(typeof(expandableobjectconverter))]     public class displaycontainer     {         [categoryattribute("xrecord data")]         public string name { get; set; } //name of collection uniquely id          [typeconverter(typeof(expandableobjectconverter)),         categoryattribute("xrecord data")]         public list<object> objects { get; set; } //list of objects manipulated          public displaycontainer()         {             objects = new list<object>();         }     } 

the object i'm wanting store instance of serialine class

    [typeconverter(typeof(serialineconverter))]     public class serialine     {         [categoryattribute("points")]         public seriapoint firstpoint { get; set; }         [categoryattribute("points")]         public seriapoint secondpoint { get; set; }         [categoryattribute("dimensions"),         readonlyattribute(true)]         public double length { get; set; }          public serialine()         {          }          public serialine(seriapoint passedfirstpoint, seriapoint passedsecondpoint)         {             firstpoint = passedfirstpoint;             secondpoint = passedsecondpoint;             updatelength();         }          public void updatelength()         {             double = firstpoint.x - secondpoint.x;             double b = firstpoint.y - secondpoint.y;             double c = math.sqrt(math.pow(a, 2) + math.pow(b, 2));              length = c;         }          public override string tostring()         {             return "first point: " + firstpoint.tostring() + "; second point: " + secondpoint.tostring() + "; length: " + length.tostring() + ";";         }          /// <summary>         ///          /// </summary>         /// <param name="pointtoparse">string representation of point in form of (x, y, z)</param>         public static seriapoint parsepoint(string pointtoparse)         {             string[] coordinates = pointtoparse.split(',');             try             {                 double xvalue = convert.todouble(coordinates[0]);                 double yvalue = convert.todouble(coordinates[1]);                 double zvalue = convert.todouble(coordinates[2]);                  seriapoint pointtoreturn = new seriapoint(xvalue, yvalue, zvalue);                 return pointtoreturn;             }             catch (formatexception)             {                 return null;             }         }     } 

which uses converter

    public class serialineconverter : expandableobjectconverter     {         public override bool canconvertto(itypedescriptorcontext context, system.type destinationtype)          {             if (destinationtype == typeof(serialine))             {                 return true;             }             return base.canconvertto(context, destinationtype);         }           public override object convertto(itypedescriptorcontext context, cultureinfo culture, object value, system.type destinationtype)         {             if (destinationtype == typeof(system.string) && value serialine)             {                 serialine sl = (serialine)value;                  return "success: " + sl.firstpoint.tostring() + " " + sl.secondpoint.tostring() + " length " + sl.length;             }             return base.convertto(context, culture, value, destinationtype);         }          public override bool canconvertfrom(itypedescriptorcontext context, system.type sourcetype)         {             if (sourcetype == typeof(string))                 return true;              return base.canconvertfrom(context, sourcetype);         }          public override object convertfrom(itypedescriptorcontext context, cultureinfo culture, object value)         {             if (value string)             {                 try                 {                     string s = (string)value;                     serialine sl = new serialine();                     string[] parameters = s.split(';');                     sl.firstpoint = serialine.parsepoint(parameters[0]);                     sl.secondpoint = serialine.parsepoint(parameters[1]);                     sl.length = convert.todouble(parameters[2]);                 }                 catch                 {                     throw new argumentexception("can not convert '" + (string)value + "' type serialine");                 }             }             return base.convertfrom(context, culture, value);         }     } 

and class points

[typeconverter(typeof(expandableobjectconverter))]     public class seriapoint     {         public double x { get; set; }         public double y { get; set; }         public double z { get; set; }          public seriapoint()         {          }          public seriapoint(double passedx, double passedy, double passedz)         {             x = passedx;             y = passedy;             z = passedz;         }          public override string tostring()         {             return "(" + math.round(x, 2) + ", " + math.round(y, 2) + ", " + math.round(z, 2) + ")";         }     } 

now, i'm getting this:

but want dropping down menu show actual objects instead of capacity , count list. thought expandableobjectconverter put on list objects in displaycontainer apparently not.