Example follows. Note the order of two AddRange methods:

public void AddRange( int[] items )

public void AddRange( Test[] items )

Change them around and everything is fine. For the above order of
declarations we'll get this from VS designer:
this.component11.Test.AddRange(new int[] { new TestApp.Test("val")});

And of course this will not build. I'm not sure anymore what the order of
declarations should be for VS 2003 designer to pick the right signature. I
guess whatever is returned last from Reflection.

public class Component1 : Component
{
public Component1(System.ComponentModel.IContainer container)
{
 container.Add(this);
}
public Component1(){}

TestCollection _test = new TestCollection();

[DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
[Editor(typeof(CollectionEditor), typeof(UITypeEditor))]
public TestCollection Test
{
 get { return _test; }
}
bool ShouldSerializeTest()
{
 return true;
}
}

public class TestCollection : CollectionBase
{
public TestCollection()
{
}
public Test this[ int index ]
{
 get { return (Test)base.List[ index ]; }
}

public void Add( Test item )
{
 base.List.Add( item );
}
public void Remove(int index)
{
 base.List.Remove(index);
}
public void Remove(Test item)
{
 base.List.Remove(item);
}
public void AddRange( int[] items )
{

}
public void AddRange( Test[] items )
{

}
public int IndexOf( Test item )
{
 return base.List.IndexOf( item );
}
public bool Contains(Test item)
{
 return base.List.Contains(item);
}
public void Insert( System.Int32 index , Test item)
{
 base.List.Insert(index, item);
}
}

[TypeConverter(typeof(TestTypeConverter))]
public class Test
{
public Test(){}
public Test(string val){}
}
internal sealed class TestTypeConverter: TypeConverter
{
public override bool CanConvertTo(ITypeDescriptorContext context, Type
destinationType)
{
 if(destinationType == typeof(InstanceDescriptor))
  return true;
 return base.CanConvertTo (context, destinationType);
}
public override object ConvertTo(ITypeDescriptorContext context,
CultureInfo culture, object value, Type destinationType)
{
 if(value is Test)
 {
  if(destinationType == typeof(string))
   return ((Test)value).ToString();
  else if(destinationType == typeof(InstanceDescriptor))
  {
   ConstructorInfo ci = typeof(Test).GetConstructor(new
Type[]{typeof(string)});
   Test test = (Test) value;
   return new InstanceDescriptor(ci,new object[]{"val"});
  }
 }
 return base.ConvertTo(context, culture, value, destinationType);
}
}