C#

private StringCollection _images = new StringCollection();

[Category("_Hotspot"),
TypeConverter(typeof(StringCollectionConverter)),
EditorAttribute("System.Windows.Forms.Design.StringCollectionEditor, System.Design", "System.Drawing.Design.UITypeEditor, System.Drawing")]
public StringCollection Images
{
	get {return _images;}
	set {_images = value;}
}

public class StringCollectionConverter : TypeConverter
{
	public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
	{
		if (sourceType == typeof(string))
			return true;
		else
			return base.CanConvertFrom(context, sourceType);
	}

	public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
	{
		if (destinationType == typeof(StringCollection))
			return true;
		else if (destinationType == typeof(InstanceDescriptor))
			return true;
		else
			return base.CanConvertTo(context, destinationType);
	}

	public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
	{
		if (value is string)
		{
			string[] v = ((string)value).Split(new char[] {','});
			StringCollection stringList = new StringCollection();
			for (int i=0; i<v.Length; i++)
			{
				stringList.Add(v[i]);
			}
			return stringList;
		}
		
		return base.ConvertFrom(context, culture, value);
	}

	public override object ConvertTo(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value, Type destinationType)
	{
		StringCollection stringList;
		
		if (destinationType == typeof(string))
		{
			stringList = (StringCollection)value;
			string result = "";
			for (int i=0; i<stringList.Count; i++)
			{
				result += stringList[i];
				if (i < stringList.Count - 1)
					result += ",";
			}
			return result;
		}
		else if (destinationType == typeof(InstanceDescriptor) && value is StringCollection)
		{
			stringList = (StringCollection)value;
			ConstructorInfo ctor = typeof(StringCollection).GetConstructor(new Type[] {});
			if (ctor != null)
				return new InstanceDescriptor(ctor, new object[] {});
		}
		
		return base.ConvertTo(context, culture, value, destinationType);
	}
}