jquery window.parent

I can use this just fine in a window

$('#dropDownSpan').css('visibility', 'visible'); 

but how can I use it in another window which is child of this window or may be opened by this wind开发者_C百科ow.

I tried:

 $window.parent.('#dropDownSpan').css('visibility', 'visible'); 

but that didnt work, any idea?

$('#dropDownSpan', window.parent.document).css('visibility', 'visible'); 

I had to interact with the parent page which had opened up a tinymce popup that I created and I needed to use this: group = $('#edit-og-groups', window.opener.document).val(); I had no luck with window.parent.document.