Hello Steve,
Thank you for writing.
RadMultiColumnComboBox gives you direct access to the popup grid via the
EditorControl property. Hence, you can get the rows count via the RadMultiColumnComboBox.EditorControl.Rows.
Count property.
I hope this information helps. Should you have further questions, I would be glad to help.
Regards,
Desislava
Telerik
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.