There is a data source for the Combo box (a service that returned a table of information bound to your combo box)
use the Selected Rows section to pick out either a full row (SelectedRows) or a single piece of information (drill down into the selected rows) to take that value and bind to other widgets.
In Thingworx mashup builder, the selection is tracked in the data source not in the widget. (except for collection widget)
