The treeDown and treeRight icons are copied from the Chromium Developer Tools.

The spinning wait icon comes from
http://www.andrewdavidson.com/articles/spinning-wait-icons/
and is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.

The warning icon comes from
http://www.iconarchive.com/show/3d-vol2-icons-by-3dlb/warning-icon.html
http://www.iconarchive.com/show/3d-vol2-icons-by-3dlb.html
http://www.iconarchive.com/artist/3dlb.html
and is licensed freeware