Comment 22 for bug 24280

Perhaps its all very difficult to explain for everyone.
Last try:

  Tolan, sudo does NOT change the theme.
  GTK just can't find the theme because it isn't looking in the right directories.

  Because the theme is installed in the users' home directory, not in /usr/share/themes.
  GTK should just use the 'home' environment value (which is correct, as you point out)