Set field read only on pick applet (QueryMode)

Hi,

I'm using Siebel 8.1.1.11 (OpenUI).

I have a customer requirement to set a field (list column) read only after setting a checkbox field to true. There is four problem with this requirement:

• It's a List Pick Applet
• Its open on Query Mode (Auto Query Mode applet property)
• It's a applet based on a VBC
• Open on product configurator

I tried using  Applet_ChangeFieldValue Event on browser script to set the field read only using this code:

function Applet_ChangeFieldValue (field, value)

{

      if (field == "FieldName" && value == "Y") {

          applet.GetControl("ControlName").SetProperty("ReadOnly", true);

      } else  {

         applet.GetControl("ControlName").SetProperty("ReadOnly", false);

      }

}

But it didn't work. Then I saw in bookshelf: