Cancel Drop Down Closing

RadMultiColumnComboBox offers the DropDownClosing event which is fired just before the pop up gets closed. This is an appropriate place to prevent closing the drop down according to any custom criteria, e.g. a certain row in the pop up grid is selected.

private void RadMultiColumnComboBox1_DropDownClosing(object sender, RadPopupClosingEventArgs args)
{
    if (this.radMultiColumnComboBox1.EditorControl.CurrentRow != null && 
        this.radMultiColumnComboBox1.EditorControl.CurrentRow.Index == 2)
    {
        args.Cancel = true;
    }
} 

Private Sub RadMultiColumnComboBox1_DropDownClosing(ByVal sender As Object, ByVal args As RadPopupClosingEventArgs)
    If Me.RadMultiColumnComboBox1.EditorControl.CurrentRow IsNot Nothing AndAlso
        Me.RadMultiColumnComboBox1.EditorControl.CurrentRow.Index = 2 Then
        args.Cancel = True
    End If
End Sub