When I installed Open SuSE 11.4 yesterday I thought that the fonts used in GTK applications like Firefox and Thunderbird were really ugly. In my KDE settings I have specified that I want it to use my KDE fonts in GTK applications but this setting seems to have no effect. To fix this I installed gnome-control-center from the repository and changed the fonts to 8 point Liberation Sans and Liberation Mono. Now the GTK applications look just as good as the KDE ones.
To make them look good the next time I log on I need to start /usr/lib/gnome-settings-daemon/gnome-settings-daemon. This is started by gnome-control-center but to make it start automatically on login I add to the auto start list in Personal Settings / Startup and Shutdown.
I'm sure that there must be some simpler way to make the GTK applications look good since I have another computer running Open SuSE 11.4 without any of the above configuration, and on that machine the KDE fonts are correctly propagated to the GTK apps. If you happen to know the reason for this please comment.