Comment 3 for bug 545134

Just ran into this problem. Synaptic and network sources are configured to use the proxy settings but software center isn't.

Seems to me that when you put the settings in "network proxy preferences" that *everything* should use it, rather than having to configure synaptic and whatever else individually. Doesn't it defeat the purpose of having that preferences panel?

I also noticed that this bug was fixed in 9.10, so the fix seems to have been lost in the transition to 10.04 (see bug 466142).