The simple question would be:
in case of iFrame are postMessage a two-way communication?
(based on https://developer.mozilla.org/En/DOM:window.postMessage)
The harder question is if the answer is yes:
why does the following don't work?
Look at both the inner frame and the main window's source.
I want simply send a message to the main window via postMessage. It
PS: the site works well on opera 9.6.3 but not on safari 4 beta