have you tried to reimport the gadgets after the changes?
Yes, I did. No effect.
NOTE: The fact that I can't import specific applications (all or nothing) seems rather weird to me also, but that's another matter.
What confuses me is that GateIn seems to ignore the .xml, .js, .css files under /webapp.
So when it presents the .xml file for me to edit within the browser, which copy of the .xml is that?
Pulled from the database?
The GateIn portal only allows me to edit the .xml file via the browser.
How do I edit the accompanying .js file, or .css for that matter?
Currently GateIn only provides such very simple gadget edition. Alternatively, let try a great IDE gadget with a online demo http://ide.demo.exoplatform.org/portal/public/classic/IDE
I tried to edit the files directly under webapps, but the modification does not get picked up.
this is cache mechanism from the gadget server ( Shindig ), you could try to clean the cache from your browser. In next versions, we could do it better by https://jira.jboss.org/browse/GTNPORTAL-773