... and document it. For now, the function is only exported internally.
This reverts commit 1f5dea9eba, since it was causeing noticable behaviour changes. Previously, GTK_DATA_PREFIX=/ ./gtk3-demo would start gtk3-demo with the Raleigh theme. With that change, it was starting with no theme at all (i.e. all black).
1f5dea9eba
https://bugzilla.gnome.org/show_bug.cgi?id=683896