KDE4 - GTK Font Fix Error was: "Gtk-WARNING **: Default font does not have a positive size"

Simply:

Must have: "Control the style and fonts used by GTK applications" in other words this: "gtk-kde4" - 74689-gtk-kde4v0.8.tar.gz

killall xfce-mcs-manager
killall gnome-settings-daemon

System Properties - System Panel - Fonts -> Choose Some Fonts NOW!. - important.
System Properties - System Panel - Use my KDE style in GTK Applications and Use my KDE Fonts
Can try different things.
RESTART APP.
If not help Repeat First step and restart again.

Cant use this for fine control: "gtk-chtheme"
Restart GTK app.