[SerializableAttribute()] 
public class PropertyTypeCollection : System.Collections.ObjectModel.Collection<PropertyType> 

class MyPage : System.Web.UI.Page
{
    public void ContextMenu()
    {
        Dynamicweb.Controls.ContextMenu FieldsContext = new Dynamicweb.Controls.ContextMenu();

        PropertyTypeCollection propTypes = Dynamicweb.eCommerce.Common.Context.PropertyTypes;
        if (propTypes.Count > 0)
        {
            foreach (PropertyType propType in propTypes)
            {
                Dynamicweb.Controls.ContextMenuButton btn = new Dynamicweb.Controls.ContextMenuButton();
                btn.Image = Dynamicweb.Controls.Icons.Icon.Type.Check;
                btn.Text = propType.Name;
                btn.DoTranslate = Dynamicweb.Controls.ContextMenuButton.TranslateStates.False;
                btn.OnClientClick = string.Format("checkTab('PROPERTY', 4, function(){{AddPropertyLine('ADD','{0}');}});", propType.ID);

                FieldsContext.Controls.Add(btn);
            }
        }
    }
}