bug#11484: 23.4; Scrolling leaves traces of old text behind

[Stefan Monnier <monnier@iro.umontreal.ca>]

> I think the better way is to do something like this:
>   if (NILP (spec))
>     signal_error ("Invalid font name", ascii_font);

OK, that makes sense, it gives me:

Debugger entered--Lisp error: (error "Invalid font name" "-Misc-Fixed-normal-normal-semi-condensed-*-13-*-*-*-c-60-iso10646-1")

but I have no idea where this "semi-condensed" comes from.  The full
backtrace shows that it was generated "internally".  My guess is that
xft returns a font info where the width says "semi-condensed", so "turn
it into an XFD and parse it back" ends up failing.


        Stefan


Debugger entered--Lisp error: (error "Invalid font name" "-Misc-Fixed-normal-normal-semi-condensed-*-13-*-*-*-c-60-iso10646-1")
  internal-set-lisp-face-attribute(default :width normal #<frame emacs@pastel 0x8a52c10>)
  set-face-attribute(default #<frame emacs@pastel 0x8a52c10> :width normal :weight normal :slant normal :font "-misc-fixed-*-r-semicondensed-*-13-*-*-*-*-*-*-*")
  font-setting-change-default-font(":0.0" nil)
  dynamic-setting-handle-config-changed-event((config-changed-event font-render ":0.0"))
  call-interactively(dynamic-setting-handle-config-changed-event nil [(config-changed-event font-render ":0.0")])