Passing javascript value to new window in firefox


I’ve been trying (and searching for a solution) for days now, but no luck.

I need to:
click a link (done)
open a new window (done)
write somevalue to that new window (not done in firefox 3.6 …)

This is the code I use to open the new window:

function poptastic(url)
	//newwindow.document.write('<p>This page was generated by    the main window.</p>');
 newwindow.document.getElementById("teksthier").innerHTML="hier dan"; 
//	var element = newwindow.document.getElementById("teksthier");
	//element.setAttribute('tekst hier', element.value);
//newwindow.document.getElementById('teksthier') = "joehoeee";
//var newdiv=newwindow.document.createElement("div")
//var newtext=newwindow.document.createTextNode("A new div")
//newdiv.appendChild("woensdag") //append text to new div
//newwindow.document.getElementById("tekstdaar").appendChild(newdiv) //append new div to another div
//var theDiv = newwindow.document.getElementById("tekstdaar");

//var existingHtml;
//existingHtml = 'donderdag';
//var j = newwindow.document.createTextNode(existingHtml);
//theDiv.appendChild( j );

newwindow.document.forms['form1'].elements['tekst1'].value = "dit hier";
 //  var target =newwindow.document.getElementById("teksthier");
//target.innerHTML = "ook hier dus"; 
	if (window.focus) {newwindow.focus()}

All the // lines I’ve tried already, none work in Firefox 3.6.

This is the doc I open, where somevalue needs to be, somewhere, anywhere!

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "">
	hallo <BR>
	<A HREF="#" onclick="chooselink('Media/gallery/40.jpeg'); return false">
<img src="gallery/40.jpeg"></a>
	<div id="teksthier"></div>
	<div id="tekstdaar">daarja</div>
	<form id="form1">
<input type="text" id="tekst1"> </input>

I cannot let javascript write the entire content of the opened page. It really needs to put somevalue somewhere so it can be used.