How to trigger an event when the ComboBox DropDownList has null value or has no datasource bound to it?

// Trigger the required event.
gridControl1.CurrentCellShowingDropDown += gridControl1_CurrentCellShowingDropDown;
 
void gridControl1_CurrentCellShowingDropDown(object sender, GridCurrentCellShowingDropDownEventArgs e)
{
     GridComboBoxCellRenderer rend = gridControl1.CurrentCell.Renderer as GridComboBoxCellRenderer;
     ListBox list = rend.ListBoxPart;
     if(list.Items.Count==0)
     {
          MessageBox.Show("ComboBox is Empty");
     }
}

' Trigger the required event.
AddHandler Me.gridControl1.CurrentCellShowingDropDown, AddressOf gridControl1_CurrentCellShowingDropDown
 
Private Sub gridControl1_CurrentCellShowingDropDown(ByVal sender As Object, ByVal e As GridCurrentCellShowingDropDownEventArgs)
   Dim rend As GridComboBoxCellRenderer = TryCast(gridControl1.CurrentCell.Renderer, GridComboBoxCellRenderer)
   Dim list As ListBox = rend.ListBoxPart
   If list.Items.Count=0 Then
   MessageBox.Show("ComboBox is Empty")
   End If
End Sub