[I'm amazed that this assertion didn't trigger until now.  I guess too
few people compile with asserts.  Or maybe most calls to
adjust_glyph_matrix don't really reallocate, since display margins are
a relatively rarely used feature.]

I'm confused about that part.  I discovered the bug using the binary build that came from  http://alpha.gnu.org/gnu/emacs/windows/.  Isn't this where most people would get their copy of Emacs 24?  Wasn't it compiled with asserts?

Tim Crews