It’s quite pathetic, that HTTP proxies settings are causing problems again and again in various applications – like UbuntuOne, pip … Maybe it is just problem for Ubuntu/Linux platforms where proxy settings are in separate places (dconf keys for desktop,
no_proxy environment variables).
This time it was Eclipse IDE. Problem here is like this – Eclipse has proxy settings in Preferences/ General / Network connections – however these settings are not applied to Help Browser (started via Help/Help Contents) – this browser is using system settings (I believe from dconf key system.proxy in my case), but not in consistent way – while browser is fine with subnet entry in system.proxy.ignore-hosts like 127.0.0.1/8, Eclipse help browser is not, it just requires server part of url – e.g. just 127.0.0.1).
Also Native option for proxy settings in Eclipse (which are used for updates, plugins install) seems not to work on Linux.
I spent some time to fix this, another victim to inconsistent proxy handling.