(defcstruct g-param-spec-double
  (:parent-instance (:pointer (:struct g-param-spec)))
  (:minimum :double)
  (:maximum :double)
  (:default-value :double)
  (:epsilon :double))  

:parent-instance

Private g-param-spec portion.

:minimum

A double float with the minimum value.

:maximum

A double float with the maximum value.

:default-value

A double float with the default value.

:epsilon

A double float value, values closer than epsilon will be considered identical, the default value is 1e-90.