tightvncserver/Xvnc running on s390x suffers from at least the following
errors:

1) The remote mouse pointer can only be moved alongside the upper top edge of
   the screen. One cannot reach and click any object (window, button, etc.)
   that is displayed on the screen. The remote mouse pointer disappears if
   one tries to do so.

2) Text in xterm is rendered displaced to the right and cropped at its right
   end, maybe by a correctly placed associated clipping rectangle. See
   attached screenshot.

This had also been discovered before by dann frazier <dannf@debian.org> when
trying to fix bug #697062. See message #27 there [1].

Tests suggest these errors are related to the 64bit big endianess of the s390x
architecture. Both errors also show up on big endian ppc64 while ppc64el works
fine.

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=697062#27