Run Function for a Specific Form on Parent Page When Readonly Field Gets New Value from Popup, or When Popup Closes

My parent page has dozens of separate forms (each row of an html table is its own form; one form per row). When any pre-populated data is changed, an onKeyUp event in that form field triggers an AJAX function to instantly update the server data for that specific form/row. Then an onChange event fires an alert ('Edits were saved').  That all works great.
     The problem is, some fields are readonly; they don't have an onKeyUp event because their data is changed only by selecting something from a popup.
    I can't use an onChange event, either, because no onChange event is triggered when a textbox gets a different value sent from a popup.
   The onFocus won't work, because I'm using a mouse click or onFocus event to trigger the popup function. So either of those events would be too soon, before the data comes back from the popup.
   I tried onBlur, but it keeps firing over and over again.

So maybe what I need is some code that will just detect that the popup was popped from that specific form, and the close event of the popup will trigger the AJAX function for that specific form on the parent page.

The code snippet shows a couple of examples of rows / forms (one uses a function that raises a popup window that contains a selectbox, and the other uses a function that raises a date-picker).


For regular fields where they can type to change the data, I just use:    
     onKeUp="ajaxFunction(this.form);" onChange="alert('Saved edits');"

What code would detect the change made in  readonly  fields (by bringing in data from the popup, or by the closing of the popup) and trigger the AJAX function as coming from the correct form (this.form)?

I'm trying to call this function from the popup function in the parent, to check if the child has been closed (and, if so, run the AJAX function), but this is not working; it is not detecting when the window is closed:

function testmywindow() {
 if (!pops[cnt].closed) {
  window.status="Child still open";
 } else {
 window.status="Child Closed.";
 ajaxFunction();
 alert('Edits were saved');
 }
}

<script type="text/javascript">
var currentField = new Array();
var pops = new Array();
var cnt = 0;
 
function windowopen(fld) {
  currentField[cnt]=fld;
 
 pops[cnt]=window.open("child.php?"+cnt,"mywindow","width=430,height=460,scrollbars=no,status=no;left=40,top=40");
 
setInterval("testmywindow();",500);
 
  cnt++;
}
 
function testmywindow() {
 if (!pops[cnt].closed) {
  window.status="Child still open";
 } else {
 window.status="Child Closed.";
 ajaxFunction();
 alert('Edits were saved');
 }
}
</script>
 
// JS popup function is called using (this.form), like this:
 
<tr>
<form name="frm_1" id="frm_1">
<td><input READONLY type="text" name="book" id="book" value="Animals" onClick="windowopen(document.frm_1.book); return false" onChange="ajaxFunction(this.form); alert('Saved edits');"></td>
<td> . . . [other <td>'s and fields] . . . </td>
</form>
</tr>
 
// ---------------------------------------
// also calling popup date-picker calendars, like this:
 
<tr>
<form name="frm_2" id="frm_2">
<td> . . . [other <td>'s and fields] . . . </td>
<td><input READONLY type="text" name="date" id="date" value="01-31-08" onClick="show_calendar('frm_2.date', '', '', '', 100, 240);" onChange="ajaxFunction(this.form); alert('Saved edits');"></td>
</form>
</tr>

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