list-add and list-remove as well as document-save are in gnome-icon-theme-symbolic. 

But unless you are exposing this in fullscreen mode, I don't think you need symbolic icons. For the sidebar, the full color icons serve the same purpose as toolbar icons. They don't need to be toned down.

http://live.gnome.org/UsabilityProject/HIG3/EditableLists
http://live.gnome.org/GnomeShell/Design/Whiteboards/SymbolicIcons/UseGuidelines

The problem isn't the toning down, the problem is that when a dark theme is used, the "colour" versions of the icons might not match the expected look/colour of the rest of the interface.

The symbolic icons look great btw. Thanks!

Can you give a specific example? We test the tango styled icons on dark background, they should work. They do tend to grab more attention but should be appropriate for the dark theme as well...

(In reply to comment #3)
> Can you give a specific example? We test the tango styled icons on dark
> background, they should work. They do tend to grab more attention but should be
> appropriate for the dark theme as well...

Not really, as we still don't have a dark theme variant for Adwaita. As soon as we have a dark variant, I'll re-test whether we should be using symbolic icons or not for the sidebar.

Created attachment 179447 [details] [review]
playlist: Use toolbar instead of button bar

This means less glade garbage, and using symbolic icons.

Created attachment 179448 [details]
using a button bar (old)

Created attachment 179449 [details]
using a toolbar (new)

As discussed on IRC, those toolbars are contextual action buttons,
not "proper" toolbars. The icons here replace what should have been
text (but wasn't in Totem).

Attachment 179447 [details] pushed as 8bc05fa - playlist: Use toolbar instead of button bar