[jQuery] jQuery UI draggable

[Thai Dang Vu]

Suppose that I have this div

<div id='draggable'>
  <div id='header'>xxxxx</div>
  <div id='content'>zzzzzzzzzzz</div>
</div>

I use jQuery UI draggable to make the div 'draggable' draggable

$('#draggable').draggable();

Then I can press the mouse anywhere in the 'draggable' div and drag that
div.
Now I want to drag the 'draggable' div only when I press the mouse on the
'header' div. How can I do that?

Thank you.