Migrating from wicket 1.2.X to 1.3 is not really hard if code has been well written (of course ;) ). Something is quite annoying : model. Models are no longer aware of component using them. Here is a simple Abstract Class making model aware of component :

[Java]
public abstract class AbstractComponentAwareModel implements IWrapModel,
IComponentAssignedModel
{

   private Component component;
   
   public abstract Object getObject();
   public abstract void setObject(Object object);
   public void detach() {}
   
   /**
    * @see org.apache.wicket.model.IWrapModel#getWrappedModel()
    */
   public IModel getWrappedModel()
   {
       return this;
   }

   /**
    * @see org.apache.wicket.model.IComponentAssignedModel#wrapOnAssignment
(org.apache.wicket.Component)
    */
   public IWrapModel wrapOnAssignment(Component component)
   {
       this.component = component;
       return this;
   }

   protected Component getComponent()
   {
       return this.component;
   }
}

Thx to Johan Compagner for the tip