I noticed a quirk in the 1.1.2 ui plugin:
After applying placing the derby core, ui, and doc plugins in the plugins dir of your eclipse installation, you can do 'Project'
>'Properties'>'Apache Derby' from the Java Perspective and modify the network server port (and derby.system.home) there.
If you have a networkserver running, the port field is grayed out, so you can only ever start 1 networkserver at a time.
But if you had changed the port, (e.g. to 1529), started a networkserver, then go back to this window, you can still press 'Restore defaults' and the port number gets reset to 1527.
This then allows you to start a second networkserver - and the toggle for stop/start has gotten reset for port 1527 also, and you cannot stop the one running on 1529 except by killing the process outside eclipse.
The 'Restore defaults' button should be disabled when network server is running.
Note: when this gets fixed, the ui (and doc, to keep them in sync) plugin version should also get updated.