Window. showModalDialog - Unable to "hold" the child window

//Code for part 1:
function openChildWindowCustodian(input){
  var myWidth = 0, myHeight = 0;
  var NewWidth = 0, NewHeight = 0;
  if( typeof( window.innerWidth ) == 'number' ) {
    //Non-IE
    myWidth = window.innerWidth;
    myHeight = window.innerHeight;
  } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
    //IE 6+ in 'standards compliant mode'
    myWidth = document.documentElement.clientWidth;
    myHeight = document.documentElement.clientHeight;
  } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
    //IE 4 compatible
    myWidth = document.body.clientWidth;
    myHeight = document.body.clientHeight;
  }
  
  NewWidth = Math.round(0.8*myWidth);
  NewHeight = Math.round(0.8*myHeight);
  window.showModalDialog('../../AccessControlASPX.aspx?myKey='+input,'','dialogHeight='+NewHeight+'px;dialogWidth='+NewWidth+'px;scroll=yes;center=yes;');
  }
 
 
 
 
 
//Codes of the 2nd page. When the button is clicked, it will invoke this javascript.
function saveandclose(){
         //var t=setTimeout("",2000); -> Does not work 
 
//This is for the button to be clicked. Note that button2 is hosting all the backend codes to be executed.
        var dd = document.getElementById("<%=Button2.ClientID%>");
        if (dd){
            dd.click();
        }
        
 
//Attempt 2: Tried to set the textcheck textbox value to 1 under the button2. so that it can "stay" in here for a while... dont work...
        var checktext = document.getElementById("<%=TextCheck.ClientID%>");
        do{
            checktext = document.getElementById("<%=TextCheck.ClientID%>");
        } while(checktext == null);
 
 
//Currently using this, works about 50 percent of the time...        
        for(var i=0; i < 1000000; i++){
        }
        
//Attempt to close the window and return to parent.
        closeWindows();
        }