Yes, I read the 'Help'.

But the help does not specify how to use the field "NO PROXY" in the "Use preset proxy environment variables". The applet detects what I write into /etc/environment as proxies, though I have no clue how to add any value into the "NO PROXY" in the last line. I have tried 'man' and 'info' on 'environment', but to no avail. I can set the "Manually specify ..." but then there is no proxy on the command line. Because at "Manual specify", it is possible to exclude specific URLs from the proxy.