title: How to disable a child item in a listview(make its color gray and unclickable)
body: <p>in my application, there is a listview, and clicking each item of it leads to an operation.</p>
  
  <p>but in some situation, some operation can not be done.</p>
  
  <p>how to disable a child item in a listview (make its color gray and unclickable)?</p>