getting id of button that triggered dialog window

getting id of button that triggered dialog window

hi.  i'm using the dialog widget, and i'm wondering how do you get the id of the button that triggered the opening of the dialog window? for example, the demo here http://jqueryui.com/demos/dialog/modal-form.html has: 

<button id="create-user">Create new user</button>

I want to be able to get the "create-user" id, but how?


thanks!