Re: MPS: face-cache

[Helmut Eller]

> Maybe the frame matrix is actually responsible for the crashes.

Actually the problem was that I forgot to revert the corresponding
igc_xfree call.  I only looked at the code and without debugger.
Stupidly inefficient.  With the correct xfree in place nothing more than
usual crashes.  So I guess it works for the glyph matrices in windows.
For glyph matrices in frames it's a bit different.  Those have a glyph
pool which must be traced too.  Are nrows, ncolumns in glyph_pool of any
relevance, or can we just loop over the nglyphs there?