To keep shapes synced, I use a reference of h glyphs and overlay a bar on it, but such self intersection is discouraged, so I just tell FontForge to care of it when generating the font, fixes #12.
This reverts part of 1d6d89c The issue this were solving turned out to be a LuaTeX bug (now fixed), also after disabling the constructed integral there is no need for the larger value. This also fixes #8. See this [XeTeX mailing list thread] for more details. : http://tug.org/pipermail/xetex/2010-October/019007.html