Make IFRAME Disabled / ReadOnly

//Paste the code inside the entity onload event box

var IFRAME_Test; 
var IFRAME_Test_Disable_Message = "IFRAME Disabled...";

function OnCrmPageLoad() {   
  //Reference the IFRAME
  IFRAME_Test = document.all.IFRAME_Test;
  //Bind to its ready state event (wait until the iframe is fully loaded)
  IFRAME_Test.attachEvent( "onreadystatechange" , OnTestIframeReady ); 
}

function OnTestIframeReady() {
  if( IFRAME_Test.readyState != "complete" )
      return;
  //Override the onmousedown event   
  IFRAME_Test.contentWindow.document.onmousedown = OnTestIframeMouseDown; 
}

function OnTestIframeMouseDown() {
  alert( IFRAME_Test_Disable_Message );
  /* or use */
  //the window is put beyond the user's desktop and is immediately closed
  var stubWin = window.open(‘about:blank’,’’,’  toolbars=0,width=100,height=100,top=10000,left=10000’);
  stubWin.close();
  return false; 
}

//Entry point 
OnCrmPageLoad();