Install private Gtk+. Assign environment variable GTK_EXE_PPREFIX to private install. If GTK+ runtime is already installed, don't set variable. Runtime will properly allow new themes and theme engines to be added/installed. Let user set Default theme, or add their own private themes, in %home%\.gtk-2.0. Must play nice with others! Private GTK, with GTK_EXE_PREFIX set, will be fall-back.
Install private Gtk+. Assign environment variable GTK_EXE_PPREFIX to private install. If GTK+ runtime is already installed, don't set variable. Runtime will properly allow new themes and theme engines to be added/installed. Let user set Default theme, or add their own private themes, in %home%\.gtk-2.0. Must play nice with others! Private GTK, with GTK_EXE_PREFIX set, will be fall-back.