Inside Master Pages

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class nestedMasters : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
		childMaster myChildMaster =(childMaster)this.Master;
		//interaction using properties
		myChildMaster.changeLocalControl("label1", "this is changed from content page");
		myChildMaster.changeMasterControl("pageTitle", "this is changed from content page");
		
		//interaction using FindControl
		Label lbl = myChildMaster.Master.FindControl("label1") as Label;
		lbl.Text = "testing";
		Button btn = myChildMaster.Master.FindControl("ContentPlaceHolder1").FindControl("button1") as Button;
		btn.Text = "by the content page";
    }
}