anchor.diff:                (4/5 (horizontally ()
                        (4/5 viewer)
                        (1/5 (vertically ()
  +                            lock-scale
                               (labelling (:label "Y Scale")
                                 y-scale)
                               (labelling (:label "X Scale")
  
positive.code:   (let ((viewer (find-pane-named *application-frame* 'viewer)))
      (with-accessors ((image gadget-value)
                       (transform-parameters transform-parameters)
                       (transform transform))
          viewer
        (let ((param 0))
          (unless (equal (elt transform-parameters param) scale)
            (setf (elt transform-parameters param) scale
                  transform nil))))
      (handle-repaint viewer (sheet-region viewer))))
  
  (defun x-scale-callback (gadget scale)
    (declare (ignore gadget))
    (let ((viewer (find-pane-named *application-frame* 'viewer)))
      (with-accessors ((image gadget-value)
                       (transform-parameters transform-parameters)
                       (transform transform))
          viewer
        (let ((param 1))
          (unless (equal (elt transform-parameters param) scale)
            (setf (elt transform-parameters param) scale
                  transform nil))))
      (handle-repaint viewer (sheet-region viewer))))
  
  (defun theta-callback (gadget degrees)
  
negative.code: (defclass spectacle-gadget (value-gadget)
    ((transform-parameters :accessor transform-parameters :initarg :transform-parameters)
     (transform :accessor transform :initarg :transform)
     (lock-x-and-y-scale :accessor lock-x-and-y-scale :initarg :lock-x-and-y-scale)
     (transformed-image :accessor transformed-image :initarg :transformed-image)
     (image-pattern :accessor image-pattern :initarg :image-pattern))
    (:default-initargs :value nil
      :transform-parameters #(1d0 1d0 0d0 0d0 0d0 0d0 0d0)
      :lock-x-and-y-scale t
      :transform nil
      :transformed-image nil
      :image-pattern nil))
  