Links in Help buffer

[Nick Roberts]

If you do:

1) C-h f display-buffer <RET>
2) Click on pop-up-frames
3) Click on customize
4) Click on the [back] button in the Help buffer

you get the error:

apply: Symbol's function definition is void: nil


This is because help-xref-stack has been set back to nil by clicking on
customize:

In help-mode.el:


(define-button-type 'help-customize-face
  :supertype 'help-xref
  'help-function (lambda (v)
                   (if help-xref-stack
                       (pop help-xref-stack))
                   (customize-face v))
  'help-echo (purecopy "mouse-2, RET: customize face"))

The error goes away if help-xref-stack is not popped but the ChangeLog says:


2000-05-09  Dave Love  <address@hidden>

        Changes mostly following Richard Sharman <address@hidden>.

        * help.el (describe-variable): Have customize button pop the
        help-xref stack when invoked.

Does anybody know why this is necessary?

Nick