namespace Nowcom.Quicksilver
{
  public interface IMessage
  {
  }
}
 
namespace Nowcom.Quicksilver
{
    using System.ComponentModel.Composition;

/// <summary> 
/// Summary description for CustomCatalogZone 
/// </summary> 
public class CustomCatalogZone : CatalogZone 
{ 
// Fields 
private ITemplate _zoneTemplate; 
 
protected override CatalogPartChrome CreateCatalogPartChrome () 
{ 

/// <summary>
 /// A replacement for the declarative catalog part meant for limiting the webparts on a page to a single instance by hiding the webparts that already exist on the page.
 /// </summary>
 [Designer ( "System.Web.UI.Design.WebControls.WebParts.DeclarativeCatalogPartDesigner, System.Design, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" ), AspNetHostingPermission ( SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal ), AspNetHostingPermission ( SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal )]
 public class CustomCatalog : CatalogPart
 {
  // Fields
  private WebPartDescriptionCollection _descriptions;
  private string _webPartsListUserControlPath;
  private ITemplate _webPartsTemplate;

public class CustomWebPartChrome : WebPartChrome 
{ 
private WebPartZone thisZone; 
private WebPartManager thisMgr; 
 
public CustomWebPartChrome(WebPartZone zone, WebPartManager mgr) : base(zone, mgr) 
{ 
thisZone = zone; 
thisMgr = mgr; 
} 

public void DateValidate(object source, ServerValidateEventArgs value)
{
    // even number?
    if (IsDate(value.Value))
    {
        value.IsValid = true;
    }
    else
    {
        value.IsValid = false;