Sets the search path for the icon theme object. When looking for an icon
theme, GTK2+ will search for a subdirectory of one or more of the
directories in path with the same name as the icon theme. (Themes from
multiple of the path elemets are combined to allow themes to be extended
by adding icons in the user's home directory.)
In addition if an icon found isn't found either in the current icon theme
or the default icon theme, and an image file with the right name is found
directly in one of the elements of path, then that image will be used for
the icon name. (This is a legacy feature, and new icons should be put into
the default icon theme, which is called DEFAULT_THEME_NAME, rather than
directly on the icon path.)
GTK2.IconTheme()->set_custom_theme()