Your change was more correct than it was. Thanks for tracking that down.

I've made some other changes that fixe other problems in the UTF8 support and fix an old problem with clipping characters that overhang the left and right ends.

If you want to take a look at current svn you should find it gives you a much tighter bounding box - check the testout/t37w32_bang.ppm and testout/t37w32_slash.ppm for examples.