anchor.diff:        :setter "cairo_set_font_face"
         :accessor font-face
         :type font-face)
  +     #?(pkg-exists-p "cairo" :atleast-version "1.4")
  +     (scaled-font
  +      :allocation :virtual 
  +      :getter "cairo_get_scaled_font"
  +      :setter "cairo_set_scaled_font"
  +      :accessor scaled-font
  +      :type scaled-font)
        (operator
         :allocation :virtual 
         :getter "cairo_get_operator"
  
positive.code:   (cr context)
    (size double-float))
  
  (defbinding show-text () nil
    (cr context)
    (text string))
  
negative.code:       :type double-float)
       (font-matrix
        :allocation :virtual 
        :getter font-matrix
        :setter "cairo_set_font_matrix"
        :writer (setf font-matrix)
        :type matrix)
       (font-options
        :allocation :virtual 
        :getter font-options
        :setter "cairo_set_font_options"
        :writer (setf font-options)
        :type font-options)
       (font-face
        :allocation :virtual 
  