Hi,

You may process ClientEvent.ValueChanged and write id of modified editor into a hidden field. On server you may process value of that hidden field and check ids of modified editors. Below is example.
If editors are located in UserControls or similar, then to find reference to modified editor on server from its UniqueID, you should use something better than simple this.FindControl(id).

<script type="text/javascript">
function editorValueChanged(editor, args)
{
 var flagElem = $get('myHiddenFlagInput');
 var id = editor.get_uniqueID();
 var flags = '|' + flagElem.value;
 // here you should use a better search (it will fail for edit1-edit12)
 if(flags.indexOf(id) < 0)
  flagElem.value += id;
}
</script>

    <ig:WebTextEditor ID="WebTextEditor3" runat="server">
     <ClientEvents ValueChanged="editorValueChanged" />
    </ig:WebTextEditor>
    <ig:WebTextEditor ID="WebTextEditor2" runat="server">
     <ClientEvents ValueChanged="editorValueChanged" />
    </ig:WebTextEditor>
    <ig:WebTextEditor ID="WebTextEditor1" runat="server">
     <ClientEvents ValueChanged="editorValueChanged" />
    </ig:WebTextEditor>
    <input type="hidden" id="myHiddenFlagInput" runat="server" />

 protected void Page_Load(object sender, EventArgs e)
 {
  if(!this.IsPostBack)
   return;
  string flags = this.Request.Form["myHiddenFlagInput"];
  if(flags == null || flags.Length < 2)
   return;
  string[] uniqueIDs = flags.Split('|');
  int iLen = uniqueIDs.Length;
  while(iLen-- > 0)
  {
   string id = uniqueIDs[iLen];
   if(id.Length > 0)
   {
    Control editor = this.FindControl(id);
    ...
   }
  }
  
 }