usp10.ScriptLayout() isn't implemented. How hard would it be to fix this?
As long as you don't use RTL scripts (such as Arabic, Farsi, Hebrew) a stub like the one I attached to the bug should do the job nicely. This goes for most of uniscribe.
A full implementation that handles RTL scripts and mixtures of RTL and LTR scripts needs a lot of work, though we may be able to leverage libicu or the recently announced initiative to create an open source, uniscribe compatible library.
We could implement it all by ourselves too of course. Ingredients would include at least an implementation of the BIDI algorithm as well as access to more properties from the unicode character database, possibly through libwine.
-Hans