Which editor (by ID) is on focus??? Please help me...

I have more then one Inline Editors in one page (each with its own ID foto_1a, foto_1b etc.)

 <TD ALIGN="left" VALIGN="top">1a: <DIV CONTENTEDITABLE="true" ID="foto_1a">Text...</DIV></TD>

 <TD ALIGN="left" VALIGN="top">1a: <DIV CONTENTEDITABLE="true" ID="foto_1b">Text...</DIV></TD>

and I use a hidden textarea form:

 <FORM ID="myform" ACTION="/cgi-bin/test/test_1.pl" METHOD="post">
  <INPUT TYPE="hidden" NAME="Url" ID="Url" VALUE="not defined">
  <INPUT TYPE="hidden" NAME="Id" ID="Id" VALUE="not defined">
  <TEXTAREA NAME="Html" ID="Html" COLS="40" ROWS="6"></TEXTAREA><BR>
 </FORM>

and a plugin with a "Save" button on the toolbar:

CKEDITOR.plugins.add( 'inlinesave', {
    icons: 'inlinesave',
    init: function( editor ) {
        editor.addCommand( 'doInlinesave', {
            exec: function( editor ) {
                var myid = "foto_1a";
                document.getElementById('Url').value = document.URL;
                document.getElementById('Id').value = [myid];
                document.getElementById('Html').innerHTML = ( CKEDITOR.instances[myid].getData() );
                document.forms["myform"].submit();
            }
        });
        editor.ui.addButton( 'Inlinesave', {
            label: 'Tekst opslaan',
            command: 'doInlinesave',
            toolbar: 'save'
        });
    }
});

to send the result to my server for replacing that part of the page.

How can I tel my server (myid = "foto_1a") from witch editor it comes? In other words: is there a function that tells me which editor (by ID) is in focus?

Thanks...