How can I get FormView_ItemUpdating notification with ManyToManyListRelationship

I have a simple:

<asp:FormView runat="server" DataKeyNames="PrimaryID" DataSourceID="PrimaryDataSource" DefaultMode="Edit" OnItemUpdated="FormView1_ItemUpdated">
<EditItemTemplate>
...
<asp:ListBox ID="ListBox1" runat="server" DataSourceID="ReferenceDataSource" DataTextField="ShortName" DataValueField="ReferenceID" SelectionMode="Multiple"></asp:ListBox>
...
<data:ManyToManyListRelationship ID="ManyToManyRelationship1" runat="server">
<PrimaryMember runat="server" DataSourceID="PrimaryDataSource" EntityKeyName="PrimaryID" />
<LinkMember runat="server" DataSourceID="LinkDataSource" EntityKeyName="PrimaryID" ForeignKeyName="ReferenceID" />
<ReferenceMember runat="server" DataSourceID="ReferenceDataSource" ListControlID="ListBox1" EntityKeyName="ReferenceID" />
</data:ManyToManyListRelationship>
</EditItemTemplate>
</asp:FormView>

Which works [amazingly] by the way...

However I'm not sure how to find out if there were any changes made to the many to many relationship
For example something like this:

protected void FormView1_ItemUpdating(object sender, FormViewUpdateEventArgs e)
{
  // Would like to do some code here if the user made any changes to the ManyToMany relationships
  // if (e.NewValues["ManyToManyRelationship1"] != e.OldValues["ManyToManyRelationship1"])
}

Anyone have any ideas?

Also, adding a

protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e)

doesn't really work as it fires after the FormView1_ItemUpdating... ItemUpdated events. 

Hi,
Because the values are never changing for the ListBox.  That's why it's not updated. 

I would except that the SelectedIndexChanged would give you the events you're looking for.  You need to add AutoPostBack="true" to the ListBox, so that it would fire this event.

Very true I did forget the AutoPostback="true" however that fires whenever a user changes the selection on the list

What I really want is to do some work when the user updates the formview... my current hack is this:

protected void FormView1_ItemUpdating(object sender, FormViewUpdateEventArgs e)
{
  if (ViewState["ChangedManyToManyLists"] != null && (bool)ViewState["ChangedManyToManyLists"])
  {
    // do some work
  }
}