Arch Linux

Sounds like firefox should be recompiled to use the *system* cairo:
http://bbs.archlinux.org/viewtopic.php?id=40990

ac_add_options --enable-system-cairo

This option is in the mozconfig file for both xulrunner and firefox, so your statement doesn't make sense.

Yeah I think this may be an upstream bug. I've included screenshots and relative info in this thread:
http://bbs.archlinux.org/viewtopic.php?pid=579688#p579688

It appears that FF 3.5 is forcing hinting (but not anti-aliasing as suggested above), regardless of fontconfig or ~/.fonts.conf settings. My ~/.fonts.conf is attached. I've also tried forcing off hinting in /etc/fonts/conf.d with no success.

When I tell GNOME not to do any antialiasing (monochrome option), refreshing the page in firefox shows jagged characters, so firefox appears to respond to settings.

Same problem here with fontconfig-lcd and cairo-lcd packages.

Jan, do the jagged characters more closely resemble my 3.0 screenshot or the 3.5 screenshot (see thread link above)?

In my experience antialiasing can be toggled, but hinting cannot and when that's the case the fonts are practically illegible. I'm not using gnome-settings-daemon however, just a simple ~/.fonts.conf. And FWIW I'm using all vanilla cairo/freetype/fontconfig packages--none that tweaked stuff.

I don't think this is a firefox bug, but rather a pango bug. Playing with the hinting settings in GNOME shows this:
None: fat characters, very ugly
Slight: a bit more fat characters, even more ugly
Medium: looks good and sharp
Full: looks good and sharp also

Or someone tell me that this is desired behaviour for hinting :P

You probably want cairo-respect-fontconfig.patch:

--- cairo-1.7.6-orig/src/cairo-ft-font.c 2008-09-29 21:43:13.000000000 +0100
+++ cairo-1.7.6/src/cairo-ft-font.c 2008-09-29 21:52:19.000000000 +0100
@@ -1705,7 +1705,9 @@
options->base.subpixel_order = other->base.subpixel_order;
}

- if (options->base.hint_style == CAIRO_HINT_STYLE_DEFAULT)
+ options->base.hint_style = CAIRO_HINT_STYLE_DEFAULT;
+
+ if (other->base.hint_style != CAIRO_HINT_STYLE_DEFAULT)
options->base.hint_style = other->base.hint_style;

if (other->base.hint_style == CAIRO_HINT_STYLE_NONE)

Info threads to wade through:
http://www.fedoraforum.org/forum/showthread.php?t=186789&page=4
http://forums.gentoo.org/viewtopic-t-511382-postdays-0-postorder-asc-start-700.html

Thanks for the suggestion, Brebs but unfortunately that didn't do the trick either.

Set up fontconfig - create ~/.fonts.conf (yes, that's a DOT at the start)
Here's mine: http://pastebin.com/f3f219efb
This solution is also at http://ubuntuforums.org/showthread.php?t=1200992

The Ubuntu solution only works however if the user prefers antialiased fonts. Disabling antialiasing doesn't work.

Disabling antialiasing doesn't work? What's the problem with this:
http://pastebin.com/f6eb48a09

Looks like antialiasing is disabled, to me. If you still think there's a problem, post your complete ~/.fonts.conf, and enable cairo-respect-fontconfig.patch ( http://pastebin.com/f6b495b17 ) in the cairo package.

I was able to resolve my issues by setting the following in ~/.fonts.conf:

* antialiasing OFF
* autohint OFF
* hinting ON
* hintstyle HINTFULL

This, for some reason, now produces the Windows 98/XP style font rendering I've been trying to restore.

i have fixed in this way: changing hintstyle from "hintfull" to "hintslight" in ~/.fonts.conf. But now why firefox 3.5 doesn't works with hintfull ? I would hintfull for my system...

I found the fix. Add this to /etc/fonts/local.conf or to ~/.fonts.conf

<!-- Firefox fix (it uses pixelsize, instead of size) -->
<match target="font">
<test compare="less_eq" name="pixelsize" qual="any">
<int>16</int>
</test>
<edit name="antialias" mode="assign">
<bool>false</bool>
</edit>
</match>

Firefox is stupid.