"icon-theme-path" property is not used in GtkStatusIcon fallback mode

If indicator-applet is not running, libappindicator falls back to a GtkStatusIcon which ignores the icon-theme-path property.

One (pretty ugly) workaround is sth. like this (vala, icons are placed in datadirectory/icons)
  // This needs to happen before get_system_data_dirs is called the first time
  var xdgdatadirs = Environment.get_variable("XDG_DATA_DIRS");
  if (xdgdatadirs.length > 0)
      xdgdatadirs += ":";
  Environment.set_variable("XDG_DATA_DIRS",
      xdgdatadirs + datadirectory, true);