Hi,

if \underbar is used inside of an overprinted test, the underbar line 
does not share the OVP attribute. Mkii works as expected, meaning the 
stroke is part of the text and should be handled equally. A minimal 
example is attached.

MTXrun | current version: 2009.11.26 16:28
This is LuaTeX, Version beta-0.46.0-2009112616

Best wishes,  Peter