Insert values into form's textarea from a popup >> insert values into {parent.post.content} from popup.

MPMU Version 2.8

I added a button that appears besides the "Add media:" buttons above the text-editor(the button thus displays/appears at two locations, on the homepage after login on the Quickpress section as well as under Pages >> Add new or Edit), my new button popups a new page with some text boxes and a submit button.

From the new popup page, I have added JS code to pass the values from this popup page to the parent page.
Eg: opener.document.post.content.value = {my_new_values_from_popup};
I even tried the code at http://wordpress.org/support/topic/300682

My JS code and the JS code from above link works fine and assigns the new_values from popup page to the textarea/editor at Quickpress section but does NOT do the same when its under Pages >> Add new and Edit.

Any help on the issue I face ?

Thanks :)