Not specific to 4.2EA, but observed there as well as with 4.0.3, both for the connection tree and the schema browser:
if you browse objects, different icons for external or temporary tables are only used when you browse another schema than the one associated with the connection.
IOW, browsing one's own tables always uses the generic table icon, whereas browsing the content of another schema will use the variants as appropriate. Odd and counter-intuitive.