This is a really big issue for me.
I've just installed Fireworks CS6 and I can't make corners rounded with the Path button. It just doesn't work, I select one corner and I click the "rounded corner" button and nothing happens.
Also, I have opened a Fireworks CS5 file that contains a rectangle with rounded corners, and when I select the two points of a rounded corner and click on the Path button to make it "square", even this does not work.
Is that a CS6 big bug or am I missing something?
I've installed the trial version on an iMac and on a MacBook Air, and both have this issue.