Found by Mathias Kosch.

Mostly based on patch from Juan Lang.

Based on a patch by Juan Lang.

ME_SplitRun is only called by wrapping code. In all but one call the
returned second half of the split run will be returned, get passed back
to ME_WrapHandleRun, then ME_CalcRunExtent will be called at the start of
ME_WrapHandleRun through ME_WrapSizeRun.

The paragraph needed to be included in the parameters to avoid needing
traverse the linked list of display items to find the paragraph.

Prevents extra copying from having to be done for converting between
unicode/ascii or between the normal or extended version of the structure.

There are unsupported flags documented on MSDN which would cause problems
for the equality checks used in EM_SETCHARFORMAT.  Also, to handle a
combined set of flags they must be checked for in the right order.

The checks for the text length and invalid parameters needed to be swapped,
and the code could be easily simplified.