Looping through all of a windows variables with "for in"

I try to loop through all the variables of a parent window using a "for in" loop:
for(i in parent) document.writeln(i+'<br>');


According to my JS docs this should return all the properties of the parent window - and it does,
but without any of it's variables. I thought that all globally defined variables automatically become
properties of the window object. Look at this:
a=1; window.b=2;
document.writeln(a);
document.writeln(b);
document.writeln(window.a);
document.writeln(window.b);
Output:
1212
But the for-in-loop only returns b, and NOT a if I place the second code block in the parent.
Any ideas how I can scan through my parent's variables without defining them all with
a "window." prefix?
___
Jpsy

Well - I just found the answer to the behaviour of the for-in-loop.
From http://www.chinalinuxpub.com/doc/oreillybookself/web/jscript/ch05_06.htm :

The for/in loop does not actually loop through all possible properties of all objects. The rules below specify exactly which properties the statement does list and which it does not in Navigator 3.0. Internet Explorer may use somewhat different rules:

• ...
• ...
• It does not list object properties or methods implicitly defined in an object with the var or function keywords. (In client-side JavaScript, defining a variable with var is the same as defining a property of the same name in the current Window object, except for the different treatment of these two cases by the for/in loop.) Properties implicitly defined by the var keyword at any time will never again be listed, even if the property is afterwards directly and explicitly set in the object. This last is not true for the function keyword.

Still I am searching for another way to find all variables by some peace of code. Maybe a false hope...
____
Jpsy

Hello there, I was actually trying to find such a solution for IE... Any success so far?

I need to duplicate a window in a statefull way... Here's my code, works only for Mozilla and opera:

function doThatThing2() {
var dup = open();
var elements = {};

// Excluding standard windows attributes of a virgin window and functions...
for (var k in window) {
if(!(k in dup) && typeof(window[k]) != 'function'){
elements[k] = window[k];
}
}

dup.document.open()
dup.document.write(window.document.documentElement .innerHTML);

for (var n in elements) {
dup[n] = elements[n];
// debug...
alert(n + " : " + elements[n] + " : " + dup[n]);
}

dup.document.close();
}