Paths to search for icons when a notification specifies a name instead of a full path. Colon-delimited. This approximates the search algorithm used by the XDG Icon Theme Specification, but does not support any of the theme metadata. Therefore, if you want to search parent themes, you'll need to add them to the path manually.
The /usr/share/icons/hicolor and /usr/share/pixmaps directories are always searched.