[Dextrose] Harmonising network proxy settings

[Sridhar Dhanapalan]

We've got at least three places in the system where network proxies
can be configured:

  * http_proxy environment variable
  * gconf
  * dconf

The latter two support manual and automatic proxies.

A problem is that different activities (e.g. Browse, Get Books) or
parts of Sugar (e.g. Software Update) want to get their proxy settings
from different sources. Also, automatic proxies don't really work in
anything but Browse (as they are JavaScript files).

All of these permutations are creating difficulties for users. Sugar
has a Proxy applet in the Control Panel, which AFAICS only updates
gconf. We've modified this behaviour in our builds to write the Manual
proxy setting to the http_proxy environment variable so that software
like yum (which we rely upon for OS updates), Software Update and Get
Books can function.

In our schools it is common to require proxy authentication to get
online, often with a PAC/WPAD file that prompts the user for
credentials when they try and access a Web page. In these schools,
they must specify the proxy twice - the Manual one first and then the
Automatic.

We commonly come across situations where teachers understandably think
they have full Internet access because Browse is able to load Web
pages. What they don't realise is that the rest of the system does not
have Internet access, meaning that (amongst other things) they cannot
update the OS or activities.

What I'm wondering is whether we can devise a means to simplify this
confusion for developers and users alike. For example, can we
standardise around one library or API call for Sugar and all
activities?