More on font corruption

[reported as bug 804191]

Following my earlier post on font rendering problems, I have spent some time investigating the issue.

A comment to my earlier post indicated that another user was seeing problems with a different graphics card.  To me, that makes it unlikely that the problem can be tied to a graphic driver issue.  It now seems likely that some software is pushing graphic hardware acceleration beyond the capabilities of the card/driver combination for some hardware.

Testing other boxes

I have since spent some time using other hardware, all with the same software (opensuse 12.3 RC1 and firefox).  I have tried an older 32 bit system with radeon graphics, a more recent 64 bit system with Intel arrandale graphics, and a 2007 desktop with nvidia 6150 graphics and nouveau driver.  None of those exhibited any problems.

Testing other software

I have since installed some additional browsers.  Here’s my current list:

Font corruption observed:

  • firefox;
  • sea monkey;
  • midori

No apparent corruption:

  • konqueror
  • rekonq
  • opera
  • epiphany (or “Web”)

This pretty much ties it to gtk applications.

Incidentally, while searching the web I found mention of Gnome terminal.  So I brought up Gnome terminal, and it doesn’t work at all.  I tried that on another computer (where I am not having font problems), and Gnome terminal still does not work at all.  So I logged out of KDE and into Gnome.  And there, Gnome terminal is fine.  So there must be some sort of incompatibility between Gnome terminal and KDE.

A web search and a workaround

Having narrowed it down to graphic acceleration with gtk libraries, I did some web searching.  And that seemed to suggest that libcairo might be the culprit.

Further searches suggested a workaround in firefox.  And it seems to work.

In firefox, browse to “about:config” and click the “I’ll be careful” button.

Look for option gfx.xrender.enabled though it might not be present.  If that option is not present, then right click and select “New”, and then add gfx.xrender.enabled as a Boolean entry.  Make sure that it is set to false.  Then close and restart firefox.

At least, for me, that appears to have solved the problem for firefox.  It does not solve the problem for sea monkey, unless it accepts the same configuration.  And it won’t help for midori (which I probably won’t use much anyway).  It also won’t help with liferea, which I do use, but the problems there were never as serious as with firefox.

At least, for the present, it is looking good with this config change.  I’m hoping that lasts, at least until the libraries are fixed.

I will post a bug report on this later today.


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About Neil Rickert

Retired mathematician and computer scientist who dabbles in cognitive science.

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  1. Browser review – seamonkey | Thoughts on computing - 2013/02/27

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