How to hide some child items on a gantt?

Let's suppose you want to hide some items on a Gantt chart, for example we have a gantt with:

• features
• and work packages as children

And we want not to show the work packages that are in a status rejected, i.e. we want not to have GNT1-542 item from picture bellow on the gantt.

To do so, put the following lines into Widget Properties > Advanced > Item Script

if(wi.getStatus().getId()==="rejected"){
  task.hide = true;
}