In 2.0 when you choose <Make unclosable> from the SystemWindow menu (downward-pointing triangle in the top right of each window), the next invocation of that menu would instead have the opposite function <Make closable>. In 3.0 it does not change to <Make closable> so you cannot revert the feature. I have isolated this to PragmaMenuBuilder's ivar 'itemList' being cached, and describe a a fix at https://pharo.fogbugz.com/default.asp?11835 However I am not comfortable with my awareness of the architectural implications and so I seek a wider discussion of this. Two queries leap to mind: 1. What is the philosophy behind caching the pragma-menus? To what degree did menu performance suffer in practice? 2. What consideration has been given to dynamic elements in other pragma-menus? 3. Suggestions for alternative resolution paths to follow? cheers -ben