Hi Falk,
Thanks for your interest in Syncfusion products.
Please refer to the following sample in which a string array is set to the DataSource property of combobox celltype' cell in gridgroupingcontrol.
http://files.syncfusion.com/support/samples/Grid.Windows/7.1.0.30/F80237/main.htmThe array of strings are shown as individual items in dropdown part which can then be selected individually.
Regards,
Rajadurai