Yep, the dithering (in this case: halftoning) is not really fit to the input parameters, I think. Thus a few "frackles" are left on pure-white areas (I think, or were it the pure-black areas?). However, this mode isn't really made for reading text. The resolution is _low_. But it was asked for, so I did it (and I was curious, too).
jmseight: It will be OK to comment out Lua, but you won't have input support then.
However there is no way around libvncclient (it brings the set of rfb* functions). It's (ironically) part of libvncserver.
http://libvncserver.sourceforge.net/ It will probably a bit of work to compile it with a TCC toolchain, though. Though I could be wrong. I never tried (yet).