To reproduce the bug:
Simply open the "Dialog and Message Boxes" in the
Gtk-demo. Type "हरि". The "ि" should be displayed on
the left of "र" but it is displayed on the right of "र".
It seems this bug is specific to Glade+gtk package,
because when I installed only gtk then there is no
problem in rendering Devanagari.
I tested on Windows-XP with "complex-script" support
enabled using the version 2.8.18.