[racket] That path issue looks related to bitmaps

Hi Jens,

That issue that you brought up in IRC: it's the bitmap, not the path.
The path is actually looking ok.  Here's a test program to show the
issue.

    https://gist.github.com/dyoo/4973820

Comment out the make-bitmap in favor of one of the other two bitmap
constructors on Mac OS X.  In the original program, under Mac OS X,
the right edge of the glyph doesn't draw for some reason.  But it does
under the other bitmaps.  So something funky is happening.