Thanks for the explanation.
You can use following sample to get the index of selected item. This code you can use in the NodeCellChange or NodeCellChanging events (get the IDropDownListService and get the selected index):
[VB.Net]
Private Sub dgParams_NodeCellChange(ByVal sender As Object, ByVal node As NineRays.Windows.Forms.Data.NodeBase, ByVal index As Integer, ByVal value As Object) Handles dgParams.NodeCellChange
If (index = 0) Then
'cast FlyGrid as IServiceProvider
Dim sp As IServiceProvider = CType(Me.dgParams, IServiceProvider)
' get a IDropDownListService instance
Dim idls As NineRays.Windows.Forms.Grids.IDropDownListService = _
sp.GetService(me.dgParams.GetType().Assembly.GetType("NineRays.Windows.Forms.Grids.IDropDownListService"))
If (Not idls Is Nothing) Then 'if it supported - receive currently selected index
Dim selectedIndex As Integer = idls.SelectedIndex
'output to diagnostics console
System.Diagnostics.Debug.WriteLine("Selected Index is " + selectedIndex.ToString())
'here place your code....
End If
End If
End Sub