Setting variable in parent document

Setting variable in parent document

Hello:
 
How does one set a variable (global) in a parent document?
 
I've tried several methods:
 
  1. parent.window['var_open']=true;
  2. window.parent.var_open=true;
  3. parent.var_open=true;
None of those methods are changing the var_open variable to true.
 
What am I doing wrong?
 
Thanks Much:
 
Pavilion