When multiple row fields and/or column fields are selected, their values are presented as tree nodes such that they could be expanded/collapsed to show/hide the next level of values. Clicking on the [+]/[-] icons should fire onPivotNodeOpen event, but it does not now.

For example, code such as the following would not show a message box when [+]/[-] icons were clicked.

<pivottable onPivotNodeOpen='alert("Node is expanded or collapsed")'/>