gtk:widget-font-options (widget)

widget -- a gtk:widget object
options -- a cairo:font-options-t instance, or nil to unset any previously set default font options

The gtk:widget-font-options function returns the font options used for Pango rendering. The (setf gtk:widget-font-options) function sets the font options. When not set, the default font options for the GDK screen will be used.