title: DropDownList in custom Grid popup editor - filter datasource
body: <p>I'm using a custom popup editor in a detail grid (several fields are using data attribute initialization).</p>
  
  <p>One of the fields is a Kendo DropDownList, but I need the options in the list to be filtered based on the value of one of the fields in the currently expanded master row.</p>
  
  <p>I've managed a buggy workaround by setting a global variable when a master row is expanded and then filtering the dropdownlist's datasource using a function call on the <code>open</code> event.</p>
  
  <p>I'm sure there must be a better way to do this. Is it possible to specify a datasource filter using data attribute initialization -- I can't see anything in the docs for this.</p>
  
  <p>Thanks</p>