Office Ribbon control: how to get the reference of a control in a custom tab

Question

Hi,

I created a custom ribbon tab for PowerPoint 2007.

The tab contains a dropdown box and a button.

In the button's callback (onAction) I would like to execute different codes depending on which item is selected in the dropdown.

However I do not know how to get a reference to the dropdown control from the button's callback. Is there a kind of "GetControlById(id)" ?

Thank you for your help!