I am using elementaryOS, which runs the Pantheon desktop environment. Currently, my proxy settings are being ignored. I reported my diagnosis of the problem.

Part of the problem is caused by the fact that libproxy checks the XDG_CURRENT_DESKTOP variable before consulting the GNOME-style configuration for proxy information. The variable is checked against a list of accepted GNOME-like desktops.

I believe this list needs to be amended with an entry for Pantheon as well. Pantheon is GNOME-like and stores the proxy configuration in the same Dconf entries as GNOME. The name Pantheon is also standardised with Freedesktop, so I would hope its inclusion here is warranted.