anchor.diff:  (defclass cepl-context nil
     ((gl-context :initform nil)
      (gl-version :initarg :gl-version)
  -   (thread :initform nil :initarg :thread)
  +   (gl-thread :initform nil)
      (uninitialized-resources :initform nil)
      (shared :initform (error "Context must be initialized via #'make-context")
              :initarg :shared)
  
positive.code: (defun init-gl-context (cepl-context surface)
    (assert cepl-context)
    (assert surface)
    (with-slots (gl-context gl-version current-surface) cepl-context
      (assert (not gl-context))
      (let ((raw-context (cepl.host:make-gl-context :version gl-version
                                                    :surface surface)))
  
negative.code:                                 :gl-version gl-version
                                  :shared shared
                                  :current-surface nil
                                  :surfaces nil)))
      (push result (slot-value shared 'members))
      (when cepl.host::*current-host*
        (on-host-initialized result))
  