So I figured out what was causing the world menus to disappear in Croquet. And this is different from the unresponsive 3.10.2 images on Vista. I know this isn't the Croquet list, I am just adding some closure here on one of the issues I raised in the newbies thread.
The problem is simple: several of the themes (appearance -> theme...) available in the Croquet zip file cause the world menus to disappear. [I will look into the details later tonight.]
Specifically, on all three Vista computers here, the themes "keihanna", "takanawa", and "westwood" cause the world menus to not be raised when invoked by mouse clicks. [The menu raised by escape generally works, but did fail in one case.] If you have pinned one of the world menus (or appearance menus) to the background, or have a workspace open, you can simply select one of the other themes to get the windows back; specifically: "outOfTheBox", "personal", "paloAlto", and "smalltalk80" all restore the world menus to the expected behavior.
This was hard for me to discover, because 1) I hadn't spend a lot of time in Croquet until everybody informed me how alpha-ish Pharo and 3.10 are, and 2) many times I wouldn't set the themes, and when I did, there was only a 3 out of 6 chance I last-selected one of the bad ones (I never chose smalltalk80 because of the strong warnings about losing the flaps), and when I did, I did not always immediately reach for a root menu - perhaps because I started pinning menus up after they appeared to be flaky.
-- What a relief... just when I was about to give up on the Croquet release. So, it seems that Croquet may work for me. I will put in some time and see if I can find some pattern to the "Vista ignorance" (of mouse and keyboard events) in 3.10.2.
-Cam