Thank you for your question.
Please refer to the following Help Article: RadMultiColumnComboBox - Overview
. As you can read there, you need the EditorControl
property which gives you the reference to the RadGridView in the dropdown.
Since the selection in RadMultiColumnComboBox is related to the CurrentRow of RadGridView, you can get a cell value by the CurrentRow
|this.Text = this.radMultiColumnComboBox1.EditorControl.CurrentRow.Cells.Value.ToString();
I hope this helps. If you have additional questions, feel free to contact me.
All the best,
the Telerik team