Is this section of the Dreamweaver API applicable to CS5? http://help.adobe.com/en_US/dreamweaver/cs/apiref/WS4FB61645-9C4E-4667-B6D4-0E5F553BEF4F.h tml The API does not seem to use the CSXSInterface, but it does seem to address Flash extensions.
Just to answer my own question:
Yes. It does apply to CS Extensions.
For example: CSXSInterface.getInstance().requestStateChange() does absolutely nothing in every test I've made in any app I've tried.
dw.flash.requestStateChange() works like a charm.
I really hope that requestStateChange() and all the corresponding events get fixed, but at least there's a workaround in Dreamweaver (where it's desperately needed because resize events are not dispatched when the swf is programtically resized...).